ATI Radeon 4650 problem

Hi,I have a little problem: I bought this graphic card (GigaByte HD4650 OC (GV-R465OC-1GI) 1GB, PCI-E)
and installed the graphic drivers from the CD. everything runs smoothly,but sometimes my screen becomes black for a few seconds and then it blinks and I get an error message:
everything runs OK then,but I don't like this thing.
I tried to get new graphic drivers,but that didn't help.could you please help me or tell me what's wrong?
Shall I give the card back to the shop?

thanks

I am having the same problem hith the same card in a desk top PC. When I play Oblivion and the screen will blank out and then return and I get an error message. Sometimes I can play for an hour with no problem, but once the problem happens, it will happen over and over again. I noticed that after this happens a couple my hardware acceleration slide is moved to the left. Eventually it is moved over enough that the game can not play at all. The problem also occurs if my hardware acceleration is tuned all the way up and I scroll a web page up or down. I have turned down my graphics setting for the Oblivion game but it didn't help. As far as my web browser goes, I don't know what to change. Any help would be appreciate.