http://firecapture.wonderplanets.de/tutorials.html has a trouble shooting video.
Firecapture is as far as I know a 32-bit application. Have you tried win 7 32-bit?
I tried win 7 64-bit, no good... FireCapture no problems, though. EDIT SharpCap...
And a few more tips here http://firecapture.wonderplanets.de/help/error.html