This means that your graphics driver is crashing involuntarily. There could be several causes for this.
a) Old/new/buggy/incompatible drivers
b) Your gfx card is overheating
c) Your gfx card is dying
A) Download the latest stable drivers for your card and follow This Link and do the steps to uninstall the old driver, then install the new one.
B) Make sure your computer has nothing blocking any of the fans
C) RMA or get a new computer.