I have the same problem. I have a Matrox G450 Dualhead, which I know is old, but Default OpenGL works fine in regular Q2.
Tonight I installed the latest drivers from Matrox's main site, and I even did a little research on the ICD and TurboGL. It seems that the G450 is no longer supported by TurboGL, or the other way around. However, the driver I downloaded tonight (and installed!) seemed to come with a ICD, which, in my understanding (limited, yes) is almost more than TurboGL was.
So I dunno. I'll keep combing the forums, I hope I can play!
PS: I read a post about the matrox G450, when I searched for it, so I have hope that this problem can be fixed!
If you guys have any suggestions, email me at Pearson.bob@gmail.com . THANKS!