Well, the problem usually happens when I try to open a movie (.wma, .avi, whatever) or even browse a folder with movies.

The symptoms are pixelated screen (reminds a TV, or like having the screen set to 400x300 resolution), only a part of the upper-left "view" fits into the screen and there's no way to fix it without restarting.

If I ctrl+alt+del all the windows, it won't help.

If I press the power button, it slowly closes all the windows and THEN it's fixed, but it doesn't help because the PC turns off in a few seconds...

PC specs:

AMD 64bit 939 3200+ Venice
Leadtek WinFast GeForce 6800GT 256DDR
Asus A8N-SLI mother board
512x2 some DDR 3200/400Mhz RAM
Some 200GB SATA-II HDD

Please help, it's DRIVING ME NUTS YARR.

I was trying to find a fix and noticed that it happens only when I had something to do with movies... So I tried uninstalling all the codecs (K-Lite Codec Pack Full) and media players (BSPlayer, Winamp, WMP-Classic and some more).

When I just deleted the codecs, it still happend. After deleting all the media players, it stopped.

After doing that, I didn't have that problem... So I reinstalled Winamp 5.1 and tried a different codec pack (Powerplayer II) and again, the problem occured.

Help me. :<

Try installing the newest version of DirectX.

You could also try updating your Geforce driver.

I got DirectX 9.0c and the latest NVidia driver.

Well, the only other things I would do (the extent of my quite limited knowlege :-) is check for an uncommon hardware configuration conflict (manufacturer FAQ or Troubleshooter) or maybe malware (although it doesn't sound like software at this point)

I actually had a wierd conflict with an offbrand video card and my MoBo
once. I called tech support for the VC and after listing a ton of options, they said something like "...and if you are using a ~ motherboard, please press...". There was some extra toolkit I had to install specially from the MoBo CD to make them compatible :-P

Hope this helps (though I'm just guessing)!