Hello D3 Forum, I have a problem that I dont know how to resolve.

When I bought Diablo 3 at the Release date I was able to play smoothly, but after a month or so, my graphic card kept crashing with the message that the graphic card had to restart itself.
That makes me unable to play because when I go in-game my graphic card will crash nearly instantly. I can be in menus or anywhere else but not in-game.
my Graphic card is: ENGTS 250DK 1GB
with 8gb of ram and AMD Athlon II 2x 250 Professor 3GHz

Any suggestions on how to resolve this problem?
Thank you.