A time ago, i got the same Error. The only thing i changed between Working/Not Working - condition, was a Ati driver update. So i installed a previous driver version and the problem was gone. To reproduce the error i installed the new driver version, but the problem never appears again. So it seems that in a few cases the Ati Setup does not install the driver correctly.
So my first question, if anyone had this problem is: Do you have a Ati?
