So for about two months I have this weird issue: 1 out of 3 flights I get a freeze of the sim - sim completely frozen, sound still playing. But here's the weird stuff:

1) This seems to mostly happen while I am ALT+TABbed out on another window (usually Firefox). I notice it when I want to go back to the MSFS window and it's frozen.

2) When I CTRL+ALT+DEL and then hit cancel, the sim unfreezes and I can continue the flight. This has worked everytime so far except twice (see below). If I don't do this, the sim stays frozen for minutes.
Sometimes I was able to unfreeze the sim also by killing a random MSFS simconnect process. While the simconnect stuff at least somehow makes sense, i have no idea what a CTRL+ALT+DEL and cancel could affect that unfreezes thesim.

3) When the sim unfreezes, simconnect resets (e.g. I can hear vRAAS reconnect and GSX stuff disappears).

4) The freezes can happen at any phase of the flight (at the gate, in the air, on approach etc.) and with any kind of aircraft and scenery, there is no pattern at all. I'm also using AddonLinker so only have the 2 airports I need for every flight, which would rule out scenery addon incompatibility as the cause.

5) Event viewer shows absolutely nothing regularly when the freezes happen.

6) Twice the freeze actually did not get unfrozen inspite of hitting CTRL+ALT+DEL - the sim then crashed after a couple of minutes and event viewer showed the W T F.DLL in the MSFS folder crashing. One of these freezes did not happen while being ALT+TABBED, but while normally in the flight.

7) The freezes almost exclusively happens with MSFS 2020, but I think I've actually had it happen once on MSFS2024 too, but seems much less there (then again I'm also using 2020 more than 2024).

Here's what I've tried so far:

- Windows Defender exclusions to each MSFS process and every external simmconnect tool and also the folders. Here's what's always connected via Simconnect when the freezes happen (in case someone has an idea): GSX (couatl.exe), vRAAS, ActiveSky, FSUIPC, MFConnector (mobiflight), RealTurb, noolaero (VDGS), AutoFPS.
- Driver updates to each and everything, windows updates.
- sfc /scannow and the componentstore cleanup
- removing the default overclocking (Alienware)

Nothing has helped so far and I'm out of ideas. The fact that it appeared out of nowhere 2 months ago and then remained make me think it's a hardware issue, I do have one of those Intel CPUs that was involved in that degradation scandal last year (13th and 14th gen) and it ran about 2 months before the BIOS was updated. However I would have thought that a defective CPU would cause much more instability - the rest of the system is very stable, no crash, no BSOD, nothing. Also it seems weird that a CTRL+ALT+DEL would just help the defective CPU to unfreeze, but then again I'm no expert.
On the other side it seems software related to MSFS because of the simconnect effects of the freeze and the possibility to unfreeze sometimes via killing a simconnect process, but this wouldn't explain why it only appeared two months ago. The only relatively "new" simconnect tool was AutoFPS, but that was already in usage (without problems) for one month prior to the first sim freeze. Could of course be an update to one of the tools that caused this (GSX, vRAAS, FSUIPC, ActiveSky, MFConnector have all been updated regularly).

EDIT:

Additional information requested:

Windows version: Windows 11 H2

PC overclocked: Not anymore and before only the factory overclock

PC overheating: Nope, temps are totally fine (70-80 degrees for CPU, 65 for GPU while running MSFS)

PC age: quite new, 9 months.

GPU: 4070ti
CPU: i7-14700kf
RAM: 32GB

Edited March 16, 20251 yr by Fiorentoni

Windows version?

PC overclocked?

PC overheating?

PC age?

17 minutes ago, vonmar said:

Windows version?

PC overclocked?

PC overheating?

PC age?

Added to the first post.

To avoid any problems with switching screens, I use both simulators (2020 + 2024) in windowed mode.
In order to switch between programs safely, I have moved the taskbar to the left-hand side of the monitor so that I can bring the desired window to the foreground with the mouse.
The problems with “ALT+TAB” already existed in P3D. I found no better way to avoid these problems than to use the taskbar on the left.

My only suggestion would be the "classical approach": to meticulously remove, one by one, each of your addons, specially those using SIMCONNECT, and see how it goes.

Start with AutoFPS, then FSUIPC if possible, ...

There were some Win 11 updates recently, more or less in line with your timing of these weird "hiccups" your simming rig is experiencing. I'm always very suspicious when weird stuff starts happening soon after a Win update 😕

Edited March 16, 20251 yr by jcomm

12 minutes ago, Alti said:

To avoid any problems with switching screens, I use both simulators (2020 + 2024) in windowed mode.
In order to switch between programs safely, I have moved the taskbar to the left-hand side of the monitor so that I can bring the desired window to the foreground with the mouse.
The problems with “ALT+TAB” already existed in P3D. I found no better way to avoid these problems than to use the taskbar on the left.

This is something I think while not directly related to the problem described in the OP, leaves, at least for me, a great suggestion, regarding the mode you run FS in but also the positioning of the taskbar !

I've started experiencing some of the effects of ALT-TABing since I purchased the WONDERFUL Lossless Scaling app, although I have enabled it's feature that allows it's magic to remain active as I leave the main / simulator window.

Your suggestion to use MSFS 2024 in windowed mode is great! I have to check where in the Graphics options that is defined.

Thanks!

Edited March 16, 20251 yr by jcomm

46 minutes ago, jcomm said:

My only suggestion would be the "classical approach": to meticulously remove, one by one, each of your addons, specially those using SIMCONNECT, and see how it goes.

Start with AutoFPS, then FSUIPC if possible, ...

There were some Win 11 updates recently, more or less in line with your timing of these weird "hiccups" your simming rig is experiencing. I'm always very suspicious when weird stuff starts happening soon after a Win update 😕

Yes there was a big Win11 update a week before it all started back in January. But I have no idea how to check if this is the culprit.

I guess I'll have to start by removing the simconnect tools one by one for testing. I was hoping someone of you guys might have a specific idea, since the CTRL+ALT+DEL -> cancel part solving the freeze seems so weird and I was hoping maybe someone of you knows exactly what the CTRL+ALT+DEL command itself does (technically seen, from a Windows perspective), so I could understand how this solves a freeze with MSFS.

Actually I've found at least three other threads on Avsim and the MSFS forums describing exactly that problem (freezing which resolves by CTRL+ALT+DEL -> cancel), but none of those found any solution or cause.

I've had an issue with MSFS 2024 (I don't have MSFS 2020 installed), where the sim freezes or becomes unresponsive. I cannot move the camera, mouse-interaction and clicking doesn't work, but the sim continues on. I can hear sounds and the instruments still functions etc. Basically, the sim becomes unresponsive to mouse/keyboard/joystick input.

Is that what you're experiencing?

16 minutes ago, anden145 said:

I've had an issue with MSFS 2024 (I don't have MSFS 2020 installed), where the sim freezes or becomes unresponsive. I cannot move the camera, mouse-interaction and clicking doesn't work, but the sim continues on. I can hear sounds and the instruments still functions etc. Basically, the sim becomes unresponsive to mouse/keyboard/joystick input.

Is that what you're experiencing?

Yes exactly that. Have you found any cause? And can you unfreeze with CTRL+ALT+DEL -> cancel?

There was at least another thread with not exactly the same symptoms, but close:

When you press CTRL-ALT-DEL, it interrupts the system and brings up the security options screen. This action can momentarily pause or reset certain processes, including those causing the freeze. By selecting Cancel, you return to the desktop, and this interruption might help the simulator recover from its frozen state.

The closest to that I've encountered so far is not being able to exit the sim to desktop. I hit the "leave" option and it stays there forever and I'm forced to kill it through the Task Manager. This actually happened to me yesterday after I made a clean install of FS 2024 and then started using it and adding new addons, but I have nowhere near to your level of "complexity" in the amount and type of external addons. 

It happened to me after installing BATC and using it for the first time, together with the default A320 NEO by ASOBO.

But after restarting the sim it didn't happen again (?)

When it happens again try:

1) CTRL-SHIFT-ESC to bring up the Task Manager Process Dashboard and find any using abnormal amounts of CPU, memory or disk access.

2) Win+ R and use "eventvwr" / Windows Logs> Application or System to check for errors or warnings while it is happening. 

3) Use the "Reliability" monitor (search for it in the Start Menu) and check the timeline of events / crashes...

😞

Edited March 16, 20251 yr by jcomm

From past experience - this appears to be related to the video card and or driver.  Are you using NVIdia overlays/filters ?  If so,  turn them off in "Settings" from inside the NVidia app. and see if this keeps happening.   

I was able to re-create a game (both 2020 and 2024) freeze whenever I popped out an instrument view and disabling the filters cured it.   Have not seen a  freeze since.

After trying that,  things like starting the sim with no community folder etc. may lead to a source as well.

Good luck

Edited March 16, 20251 yr by Tony P

Would you happen to be using Lossless Scaling? It does this from time to time and not only does the program sound keep going but it's actually still running where it was heading when the freeze occurs. You'd be surprised how this affects American Truck Simulator. I have hit bridges, houses, walls but it sure was smooth up to that point... 🙃🙃🙃

27 minutes ago, Pivot said:

Would you happen to be using Lossless Scaling? It does this from time to time and not only does the program sound keep going but it's actually still running where it was heading when the freeze occurs. You'd be surprised how this affects American Truck Simulator. I have hit bridges, houses, walls but it sure was smooth up to that point... 🙃🙃🙃

Nope, am using native Frame Generation. I mean this is similar, but as said above none of that happened within the first 5 months using it, only January this year it started.

UPDATE: So as for the cause and "solution" - it was indeed caused by one of the Win11 updates. It basically only happens when I constantly ALT+TAB in and out. It almost never happens when I use the windows key, and then click on another window.

On 3/16/2025 at 8:49 AM, Fiorentoni said:

UPDATE: So as for the cause and "solution" - it was indeed caused by one of the Win11 updates. It basically only happens when I constantly ALT+TAB in and out. It almost never happens when I use the windows key, and then click on another window.

----------------------------------------------------------------------------------------------------


So for about two months I have this weird issue: 1 out of 3 flights I get a freeze of the sim - sim completely frozen, sound still playing. But here's the weird stuff:

1) This seems to mostly happen while I am ALT+TABbed out on another window (usually Firefox). I notice it when I want to go back to the MSFS window and it's frozen.

2) When I CTRL+ALT+DEL and then hit cancel, the sim unfreezes and I can continue the flight. This has worked everytime so far except twice (see below). If I don't do this, the sim stays frozen for minutes.
Sometimes I was able to unfreeze the sim also by killing a random MSFS simconnect process. While the simconnect stuff at least somehow makes sense, i have no idea what a CTRL+ALT+DEL and cancel could affect that unfreezes thesim.

3) When the sim unfreezes, simconnect resets (e.g. I can hear vRAAS reconnect and GSX stuff disappears).

4) The freezes can happen at any phase of the flight (at the gate, in the air, on approach etc.) and with any kind of aircraft and scenery, there is no pattern at all. I'm also using AddonLinker so only have the 2 airports I need for every flight, which would rule out scenery addon incompatibility as the cause.

5) Event viewer shows absolutely nothing regularly when the freezes happen.

6) Twice the freeze actually did not get unfrozen inspite of hitting CTRL+ALT+DEL - the sim then crashed after a couple of minutes and event viewer showed the W T F.DLL in the MSFS folder crashing. One of these freezes did not happen while being ALT+TABBED, but while normally in the flight.

7) The freezes almost exclusively happens with MSFS 2020, but I think I've actually had it happen once on MSFS2024 too, but seems much less there (then again I'm also using 2020 more than 2024).

Here's what I've tried so far:

- Windows Defender exclusions to each MSFS process and every external simmconnect tool and also the folders. Here's what's always connected via Simconnect when the freezes happen (in case someone has an idea): GSX (couatl.exe), vRAAS, ActiveSky, FSUIPC, MFConnector (mobiflight), RealTurb, noolaero (VDGS), AutoFPS.
- Driver updates to each and everything, windows updates.
- sfc /scannow and the componentstore cleanup
- removing the default overclocking (Alienware)

Nothing has helped so far and I'm out of ideas. The fact that it appeared out of nowhere 2 months ago and then remained make me think it's a hardware issue, I do have one of those Intel CPUs that was involved in that degradation scandal last year (13th and 14th gen) and it ran about 2 months before the BIOS was updated. However I would have thought that a defective CPU would cause much more instability - the rest of the system is very stable, no crash, no BSOD, nothing. Also it seems weird that a CTRL+ALT+DEL would just help the defective CPU to unfreeze, but then again I'm no expert.
On the other side it seems software related to MSFS because of the simconnect effects of the freeze and the possibility to unfreeze sometimes via killing a simconnect process, but this wouldn't explain why it only appeared two months ago. The only relatively "new" simconnect tool was AutoFPS, but that was already in usage (without problems) for one month prior to the first sim freeze. Could of course be an update to one of the tools that caused this (GSX, vRAAS, FSUIPC, ActiveSky, MFConnector have all been updated regularly).

EDIT:

Additional information requested:

Windows version: Windows 11 H2

PC overclocked: Not anymore and before only the factory overclock

PC overheating: Nope, temps are totally fine (70-80 degrees for CPU, 65 for GPU while running MSFS)

PC age: quite new, 9 months.

GPU: 4070ti
CPU: i7-14700kf
RAM: 32GB