Sorry for the late response.
I ve had the same problem together with several other cs4 software errors. This happened to me before also, but this time after setting up an old version VGA driver (to operate my stereoscopic gaming devices)
Some of he messages were about the newly introduced GPU acceleration or something like gpu sniffer, so I thought this might be a VGA driver related issue. I have an NVIDIA 8600 GT graphics adapter. Setting up the latest drivers againe, solved my problem in all adobe applications.
Although your adapter is ATI, it may well have similar problems with adobe’s gpu acceleration.