1. A 32-bit app can't directly address the data structures of a 64-bit OS, therefore the OS must replicate a 32.bit version of any data structure accessed by the 32-bit app and do so inside that 32-bit app's address space. Therefeore the 32-bit app can't use the entire 4 GBy or it would not be possible for that app to communicate with the OS. 2. Apologies, my wires got crossed! /USERVA is of course not obsolete, what's been obsoleted is the need to physically patch the fsx.exe to make it /USERVA-aware. Cheers, - jahman.

I had this problem about a month ago. After searching the web and the forums I tried moving the most recent flightplans I had installed (about 2 weeks worth) to my Temp folder. FSX then started without the error. I added the traffic.bgls one by one until one caused the issue. I deleted that one and redownloaded it and haven't had the problem since. A bad .bgl file can cause this error. Check it out. Steve LewisAIG Dispatch

1. A 32-bit app can't directly address the data structures of a 64-bit OS, therefore the OS must replicate a 32.bit version of any data structure accessed by the 32-bit app and do so inside that 32-bit app's address space. Therefeore the 32-bit app can't use the entire 4 GBy or it would not be possible for that app to communicate with the OS. 2. Apologies, my wires got crossed! /USERVA is of course not obsolete, what's been obsoleted is the need to physically patch the fsx.exe to make it /USERVA-aware. Cheers, - jahman.

1. OK if you know it's like that, but why does it then show usage up to 4GB and crashes if it wants more?

1. OK if you know it's like that, but why does it then show usage up to 4GB and crashes if it wants more?

Not sure about that. Perhaps since the 32-bit OS stub is one per 32-bit app, the stub address space is tagged as part of the app? Cheers, - jahman.

Not sure about that. Perhaps since the 32-bit OS stub is one per 32-bit app, the stub address space is tagged as part of the app? Cheers, - jahman.

I never ever heard anything about this "stub" you are talking about, whatever that is. I googled it, but found no plausible definitions. And you are by this definition the first one here to say something like this.I can also take a comparison that under XP 32bit, I was able to use 2GB of RAM, with the tweak, 3GB, and then under 64bit the usage was same for the same config (I remember back then I used to do a lot of testing in that area), and then I pushed the envelope further to 4GB.But with FS9, same installation being used in XP and Win7, I confirmed that virtual space used was the same in both OS's.

I never ever heard anything about this "stub" you are talking about, whatever that is. I googled it, but found no plausible definitions. And you are by this definition the first one here to say something like this.I can also take a comparison that under XP 32bit, I was able to use 2GB of RAM, with the tweak, 3GB, and then under 64bit the usage was same for the same config (I remember back then I used to do a lot of testing in that area), and then I pushed the envelope further to 4GB.But with FS9, same installation being used in XP and Win7, I confirmed that virtual space used was the same in both OS's.

Try here Word Not Allowed, went over my head. :) So not sure if this is what you mean. I would rather eat a kilo of baked beans sitting in a telephone box than read what is in that link. http://lafaix.online...s2/contest.html

To come back to my original subject: I think I will try a repair install. I have FSX-Sp2 installed.I have made some research about the repair install in the forum.They say one must first desinstall Sp2 and Sp1 and then do the repair and afterwards reinstall SP1 and Sp2.Seems logical to me. Is that right? It is also important to save before the repair the following files:fsx.cfg, dll.xml, scenery.cfg and all the modfied default files , aircraft.cfg etc.Are there other files to save? Thanks Guy

I had this problem about a month ago. After searching the web and the forums I tried moving the most recent flightplans I had installed (about 2 weeks worth) to my Temp folder. FSX then started without the error. I added the traffic.bgls one by one until one caused the issue. I deleted that one and redownloaded it and haven't had the problem since. A bad .bgl file can cause this error. Check it out. Steve LewisAIG Dispatch

That helped! About two weeks ago I had modified also, like you, a traffic Bgl file.I now recompiled that Bgl file again without those modifications.And ... FSX RESTARTS now ! and I can fly! I still get a message at startup saying "DLGALERT.bmp could not be laded" .That is the box with the progress bar.But this doesn't hinder the startup. I will try to sort that out also. Many thanks!!!! Guy

Yupp - this message refers to the image of the box in which you see the progress bar while things load. It is to be found in the "Uires" folder. If it's gone, you can get it here:- http://www.mediafire.com/?v0l48si9k8zw8

Yupp - this message refers to the image of the box in which you see the progress bar while things load. It is to be found in the "Uires" folder. If it's gone, you can get it here:- http://www.mediafire.../?v0l48si9k8zw8

Thanks for your answer and the link. As I have Fs9 still on the Pc I replaced already the Dlgalert.bmp of Fsx by the one from Fs9.(The only difference is, the one from Fsx has a red border and the one from Fs9 has a grey border!) So this problem is also solved now and EVERYTHING seems OK again! Thanks again to all (and especially Steve Lewis) for your help! Guy