I upgraded to Parallels 7 back in April, and have been using it since then without any problems. I have three virtual machines with Windows 7, Vista, and XP. Today when I opened Parallels, it prompted me for my license see. I entered it, and then it said I didn't have any virtual machines! What can cause this? Does this suggest a corrupt preference file? I know I can manually find and open my virtual machines, but I don't want to have to re-set all of my preferences.