I have a rather strange problem. Occasionally when I boot, the GRUB screen has lots of black lines across it, and the screen is at a low resolution. If I let it boot through to Windows 7 or Ubunutu (12.10) there is no graphics card deteced. In all cases, rebooting works fine. In fact usually I just press the reset button at the GRUB screen and it always works.
It kind of seems like it should be a problem with the graphics card (GTX 460), except it always works after a reset. I guess then, something with the BIOS may be causing it? The motherboard is an Asrock Z68 - I'd have to double check for the exact model.