Flickering and Freezing during game

When I play graphics-intensive games on my Vista (specifically, Warcraft III,
Maplestory, and Dawn of War), my screen often begins to flicker. The
flickering grows more and more frequent, until the computer blacks out and
freezes for about a second. It's bearable, but it's never happened before on
my XP, and it's quite irritating, because this hardware error happens very
frequently (About 2 times per hour).

The computer always complains about some sort of "problem caused by Intel
Graphics Driver". What can I do to fix this? Should I get a new driver? And
if so, where would I get one?

Thanks.