Missing emails

Running Groupwise 2012. All of a sudden all messages older than January of this year are gone from a mailbox. Gone from Inbox, and all Cabinet folders. The cabinet folders still exist but nothing but messages from this year are there. I've already run a Structural rebuild on the affected user. We are receiving a Problem 39 in the report, but that being said, I ran a structural rebuild on another mailbox and got the same problem id. User was running his client in caching mode and DID NOT delete the messages (he's a system admin and not the typical end user).........So, has anyone run across this problem and is there a way to fix it?