Cannot delete Personal Distribution List from Mailbox

Exchange 2010 SP2 RU5 v2

I have a user who has 2 personal distribution lists that outlook reports as "corrupt".

I have:

a) checked for corruption in his mailbox (none found)

b) moved his mailbox to a different database (no corrupted items reported during move)

c) logged onto his mailbox with MFCMapi and tried to delete them.  No errors, but they do not delete.

Any ideas on how I can remove these items?

Thanks