I've been running ATI for awhile now so I'm not really qualified to provide a definate (read: any kind of) answer ... BUT ... ATI did have some OpenGl issues in older games (IL2) awhile back and one either had to backdate the video driver to one that worked OR pull the atioglxx.dll file from the driver that worked, expand it, and drop it into the game main file so it would over ride the newer driver's verson. So, maybe you could try older drivers and, if that works ... keep it or try digging around in it for the opengl dll file ... maybe ... I don't know ...

Another thing to look at might be memory allocation/reporting.

Good luck.