Windows 7: Black Screen after video playback (random)

Hello everybody,

I have a very weird issue with Windows 7 (64-bit) on my computer.

First of all, it has been happening ever since I installed Windows 7, it did not occur after a specific update or installation.

My computer will show me a black screen and completely freezes AFTER video playback, however not always.

I have this problem with media player 11, media player classic, quicktime, and embedded video on websites (both IE and Firefox)

As long as the video is playing, I have no problems. If the video end, still no problem. However as soon as I close the screen containing the video (be it either een media player or a browser tab with embedded video) the computer gives me a black screen and completely freezes.

It does not happen everytime. Sometimes I can go by days without any problems, sometimes I have it several times a day. The only constant is dthat it happend as soon as I close the video window.

I have tried BIOS upgrades, upgrading chipset drivers and video drivers whenever new versions came available, but it does not help.

My computer is running perfectly fine besides this video issue. I can play al kind of games (Red Alert 3, Starcraft 2, Crysis,...) without any problems or crashes. I can play video files, but standard and HD formats, without any problems (as long as they are playing)

But whenever I close a window with a video inside, it's a 50% chance of complete freeze with black screen.

Also, I can't find any info in the windows event viewer logs, no info seems to be written here when the computer freezes.

Anyone provide me with solutions, suggestions, things I might try?

Thank you very much!

Asus P6T SE with Intel i7-920 and 6 Gb DDR3-1333 / Radeon HD4850(512Mb)
Windows 7 64-bit Ultimate