I had the same problem. I have a roaming profile and I got a new PC. I did not load MapPoint SW on th new laptop so I got this error because it followed my profile.

I didn't find any file names, ComAddins, etc.. that referenced file name 'mpoai9.dll'.

Ultimately I searched the registry for 'mpoa' and deleted all keys that contained a matching value. Interestingly, they were under HKLM\Software\Microsoft\Office\ (Word, Excel, Powerpoint, Outlook)\Addins. Choose your app in parenthesis.

So, they were in the registry under 'Addins' but they were not in the ComAddins options within the applications.

Once I deleted them, the problem went away.