I can confirm the above advice is good also my experience.

I reformatted and reinstalled Windows after repartitioning my drive then re-installed MSFS in December. Since then so far so good, and pretty smooth at HIGH end settings on a 7 year old machine.

The previous installation of Windows was seriously not OK.

Interestingly I had been using CCleaner to clean the registry amongst other things. Don't do it - is excellent advice. Normal clean up is probably OK if you are careful and vigilant, but never completely delegate to these programs and sit back.

Note I never suggested to blindly use tools like CCleaner. But I find it overkill to reinstall Windows if just one 3rd party software does not work anymore but everything else is fine. In such cases it's better in my experience to remove everything of that 3rd party app (incl its registry entries) and then try reinstalling that app.

Thank you, everybody!

I finally reinstalled Windows 10 because all the other methods didn't work.

I used the tool "MediaCreationTool" with the option keep everything (programs and data).

The problem it's solved partially (I can't install DXO filters and Photoshop last update, but surprisingly I could install the previous version!). I can live with that!

Flight Simulator is all right, not affected.

Thanks also to RaptyrOne, Car147, Gernil, Barnes and rayharris108 for your advice and support.

I assure you that if anything more fails I'm going to reinstall Windows, because it seems that it's not difficult to install again MSFS 2020.  

One more question just in case: Should I uninstall MSFS before installing windows?

Thank you.

 

If some program you use had a problem don`t rush to re-install if it needs net connection.

Massive internet outage hits websites including Amazon, gov.uk and Guardian | Internet | The Guardian

I had a problem with steam and COD yesterday, lets hope it`s not a sign the cloud is getting weak and overloaded.

2 minutes ago, G-RFRY said:

If some program you use had a problem don`t rush to re-install if it needs net connection.

Massive internet outage hits websites including Amazon, gov.uk and Guardian | Internet | The Guardian

I had a problem with steam and COD yesterday, lets hope it`s not a sign the cloud is getting weak and overloaded.

Thank you, G-RFRY!

I take note of that!

 

1 hour ago, MarioDonick said:

Note I never suggested to blindly use tools like CCleaner. But I find it overkill to reinstall Windows if just one 3rd party software does not work anymore but everything else is fine. In such cases it's better in my experience to remove everything of that 3rd party app (incl its registry entries) and then try reinstalling that app.

"Cleaning up the registry" is almost always terrible advice for folks that do not know what they are doing, can't use a hex editor, etc. Many programs dig so deep into the operating system, that a simple "uninstall" won't do.

There are essentially only two viable steps:

1. Get help from a professional

2. Follow the above steps to a)reset windows, b)download needed windows updates, c) remove old drivers (carefully following the uninstall instructions on the respective manufacturer's websites), d) install the latest drivers, e) reinstall your apps, including MSFS 2020.

It might take a few hours but that is the safest way to proceed.

Hi, everyone!

Finally, I decided to reinstall Windows 10 from scratch (how daring I am!) because there were alarming signs of SO malfunction. 

First, I uninstalled Flight Simulator, then I installed Windows. Everything went smoothly. 

So, in principle, it seems to me that Flight Simulator can be reinstalled after reinstalling Windows 10 without problem.

Thanks again to everyone who answered this topic and helped me.

🙂