I had the same thing happen and followed your directions, everything seems fine now. Lucky for me I noticed when the restart dialog warned me it was going to delete my stuff, so I hit cancel and backed up my Home Folder using both Time Machine and .Mac Backup, just in case. But yeah, if you get this message, just kill loginwindow, log back in, and then restart.
FYI to everyone, turn off Guest Account, it's too dangerous the way it is. Hopefully apple will fix it, or at least offer the option to disable the whole "delete the account when done" "feature"