I successfully installed beta 3 on my iMac last week installed Win XP Pro, and then updated Perallels to beta 4. Last night, Win XP refused to run, returning to the Parallels configuration window immediately after loading. I trashed the Parallels folder, which led to weird Finder behavior. Disk Utility found multiple errors, which were fixed. I then re-installed beta 4 and Win XP, which ran fine this morning. This evening, with no intervening activiy, the VM is gone - the Parallels folder is empty. (I'd done a save state before shutting down the Mac this morning.) Everything else is running fine. Comments?