Gtx295 problem - need help

hi, i have some problems with my zotac gtx295

for example in crysis warhead, after a while i get a problem like this -> http://img196.imageshack.us/img196/1461/problem1x.jpg
i don't know the exact words for this problem, sorry for my english. colors turn into different ones.
after alt-tab and return to game, it looks like the problem is gone, but after like 10minutes here it comes again
temps when this problem occurs are between 83-90 (auto gpu fan)

in call of duty world at war, there were flickering things and rectangles in smoke textures
even in fifa09, sometimes i get similar errors like there is a player face texture covering the whole screen or inverted colors

is this a problem with hardware or software? cuz i installed 185.85 and 186.18 and the problem still exist
i don't know what to do now, sending my card for a new one? or what?

p5q deluxe
q6600@3.0
kingston hyperx 2x1 @1066
zotac gtx295 default clocks
tt toughpower 750W