I would first try by cleaning your cache and trashing your preferences (Premiere Pro) and a restart of the PC. If the problem still exists, then I would uninstall and reinstall the Matrox drivers. Also, you should look if there are newer versions of the drivers for your MXO mini with Win7.
If that fails, then post here again.
Thanks so much for the reply. Would you explain how to clear the cache and trash my Premiere Pro preferences? I'm going to reinstall Matrox again to see if it helps and also update my audio driver for my Xonar card to see if this helps. I'm a bit worried that my last OS reinstall missed something. When I installed the Matrox mini software the first time around, I got an indication that said I had no media controller - not sure what that would be. Cheers, Steve
clearing cache Premiere Pro preferences>Media You will see a clean button.
Make sure you do everything in it's proper order - try this first and only then do an uninstall/reinstall of the Matrox.