I'd start with a db repair, assuming you didn't try that already.

If that doesn't work, it could be a corruption in the online profile list. Just remove the following 2 files

OnlineList.dod
OnlineListSel.dod

located in: C:\Users\Username\AppData\Roaming\DVD Profiler (for Vista and Win7, path will be different in XP)

I had that problem a few months back and a repair fixed it for me.