Geforce 280 GTX Errors. Please assist.

Hi all,
My GeForce 280 GTX has very recently begun acting strangely. Whenever I boot a game or visit youtube or any website with streaming video the Graphics card suddenly stops rendering and fills the screen with a garble of pink and green artifacts. 2 seconds after this the monitor goes into standby mode as if the card has ceased outputting at all.

System Information:
Windows Vista x64 Home SP2
6GB RAM
Quad Core Intel CPU @ 2.66 Ghz per core.

I have reinstalled the drivers and this fixes the issue, but the next time I reboot the computer the problem returns until I reinstall the drivers again.

Is this a hardware issue, is this driver related (such as conflicts)?

I will be testing a replacement card in a day or so, but could anyone think of any causes that aren't directly related to faulty hardware (i.e. dead card)?

Your assistance much appreciated.

EDIT: Just to confirm completely removing (via add/remove programs) the Graphics Card Drivers and then reinstalling them clears the error. However, once the computer has been restarted the error returns until the driver uninstall/reinstall provess has been repeated. This would seem to rule out a hardware fault. I have also tried multiple Nvidia driver versions, including Beta drivers and full release-version drivers. All result in this error.