I started the database maintenance. It's been running for over an hour now. Is this supposed to take that long?
Database maintenance can take a while if you skipped maintenance several times. Remember: this database contains the names of all files installed along with the applications you installed. If this number gets bigger and bigger, you may have to wait a little while CleanApp dusts off for you.
This is not supposed to take hours, though. If you don't see any progress whatsoever after a while, please stop the database maintenance and start again. If this doesn't help, the best way to get CleanApp running again is to delete the database.