Sims 3 crashing - graphics card not supported

Hello,

My Sims 3 keeps crashing randomly - sometimes when I'm trying to save, or just while I'm playing. When I try to restart the game it comes up with a windows warning thing saying something like the graphics card isn't supported. If I remove the disk - wait a minute and put it back in, the game will run again...
I have just had a ATI Radeon 4350 card installed - but the Sims 3 system requirements don't state whether it should be compatible?

Does anyone else have this card and have problems - or know if this card can be used? Maybe its something else causing the crashing, but thought I should investigate this first...