Yes now i did try sfc /SCANNOW but everything is normal. and no yellow exclamation marks in the device manager.
I might add that the two times my pc crashed I was using application that needs the vga to run . one time it was a game and one time I was using 3ds max.
Now its been two days using the pc constantly without using an application that requires the vga to run. And everything seems okay.
could it be a vga failure or overheating?? but then why again when i restart i cant see my desktop ...
Anyway thanks for the tip.