One of my worries with window 7 was sonic stage not working, but all was fine with beta and then RC1 versions, I now use the Home Premium and all is fine. Try running compatability mode with XP instead of Vista, if that doesnt work uninstall SonicStage and reinstall, dont drop a copy on top of what you have ( I think it uninstalls anyway..) If you havent already.
One more thing, have you a different USB port you could use, I have one that is a devil at times and is never used anymore.