This is the first time I've encountered a problem with Parallels. First, every time I open it I'm getting a black screen. And once I've minimized and reopened Windows I'm unable to open any program. Please help!!!!!!
I think it's fine to attempt a repair as described in the previous posters link. However, I always backup my virtual machines weekly. If you have such a backup, then you can copy the backup to the Parallels folder. You'll be good to go. You can even rename it and then you step four of the previous posters link to copy data from one VM to another VM.
P.S. I use Carbon Copy Cloner for weekly backups. it only copies changed files and is fairly simple to use. I recommend it.