Sounds like you are using the latest ATI drivers for the card?

I had a lot of problems with ATI drivers a long time ago and that is why I switched to NVIDIA cards. I know nvidia is not on top of the performance chart atm but I have always found their drivers to be much more stable then ATI.

I have a friend that uses ATI cards though and runs Maya I will drop him a line and see what feedback I can get from him.