Thanks for your feedback. I'm glad it works, and it was actually not only XP64 that had the problems. Tried in a 32 Bit XP on an older machine and got the same error, so I guess it's best to leave WMI out of the app. And yes, I don't think it's important to know wether the report is from a 64 or 32-Bit machine as the OpenGL capabilities should be the same for the same driver.

And as for logging GL calls, have you tried GLDebugger. It became freeware some time ago and is a pretty in-depth debugger for OpenGL apps.