Hello, this is my first post on this forum, so I want to say "hi" to everyone

!
I've already posted this problem on a different forum, but I got no solving answers yet, so I copied the content here and modified it with every additional info I got from the other forum.
I've got a strange problem with every PC game I play:
Some time ago I used to play Sniper Elite v2 for a long time, the game worked fine, but at first it had no sound. I couldn't solve that problem until I realized that updating DirectX by dxwebsetup.exe (DirectX updater) solves the problem. In fact I already had the newest version of DirectX, but dxwebsetup installed some optional DirectX components that weighted about 43MB (not sure if EXACTLY that much). It's probably the moment my problems started.
As soon as I got bored with SE v2 I stopped playing any games for like a month or so, had no problems with my PC etc. It was like that until I installed FIFA 12. Game worked great for the first 5 minutes (till a while after the second half starts), then it would crash. EVERY TIME, no exceptions. I was really disappointed so I installed FIFA 11, which worked fine but also had some random crashes (never as much as FIFA 12, but still it would crash once every five matches). That was the time when I thought that something bad is happening.
So I formatted the system partition to install a fresh copy of Win 7 (I also used dxwebsetup again, which installed same optional features as before). It didn't help. FIFA 12 was crashing the same way, so was the FIFA 11 every five to ten matches. I hoped for the fact that it's a problem connected only to FIFA series.
Sadly, I was wrong.
My next game was NBA 2k12 which I used to play aloooot the previous year (like 200h of gameplay) and it never crashed then. NEVER. But today I can play about 5 to 10 minutes of NBA 2k12 and it crashes every time. Then I tried L.A. Noire. Same story, crashes after about 5 to 10 minutes. EVERY game has a tendency to crash after almost the same amount of time.
Before you suggest:
- The sound problem with SE v2 was the game's issue, not the PC's, I know it because many people experienced the same problems with this game. Using dxwebsetup solved any sound problems. Every other game had sound and it worked fine.
- My graphics and audio drivers are perfectly up to date
- I tried to update DirectX
- I tried to switch back to previous graphics drivers
- I tried to install older DirectX redist.
- I tried using dual core optimizer
- I tried reinstalling MVS C++ redistributables
- I checked if the PC is overheating, it's not
- Only hardware change before the crashing spree, was changing my NEC 17' monitor (DVI Input) to a BENQ 15' monitor (connected via adapter [DVI-graphics card output] -> [D-SUB-monitor input]) - crashes actually started to occur after this monitor change, however I wasn't playing any game for a while before it, so you know, I may have had no occasion to encounter them
- I tried removing DirectX from the registry and installing it again
- There are no other problems than those crashes, except for them, games work perfectly normal
- Games tend to work perfectly in windowed mode (tested on NBA 2k12), crashes occur in full screen mode only.
- I can't uninstall those optional DirectX components from the system because they are not listed in the Add/Remove Programs menu
- Playing in different resolutions doesn't help
By "crash" I mean a complete crash to desktop without any error at all or in some cases with a standard Windows 7 error stating that an application stopped running, but more often there's no error at all.
Do you have any suggestions on my problem? I would be so grateful for any help, thank you.