Sorry for the late response. I´ve had the pc checked out by a computer workshop and they said that even to them the problem is a mystery.
Theyve taken out the video card and replaced it with another one and it works fine. then they took the video card and tried it on another system and it was also fine.
Basicly the video card no longer works on my system but it DOES work on other systems. I also mentioned installing the beta drivers to them and they said the same thing Qwixt says. They are now trying to remove the drivers and see if that works, i´ll probably hear from them tommorow.
If anyone has any other ideas of how something like this can happen I´d like to know