I have a user who cannot activate in the BES Manager. We keep getting "Old OTAKEYGEN packet is cancelled tag=xxxxx". However, if I create a new user and mailbox, his device can activate just perfectly. We had an Exchange server crash a few days ago and were forced to perform a hard repair. Clearly this damaged his BB data in some way.

Other than exporting the mail to pst, deleting the mailbox from exchange and creating a new store and reimporting the mail, is there another way to clear out what could be orphaned Blackberry data on the user mailbox? All other BB users are unaffected by this problem.

Try moving the mailbox to a different storage group.
That should clean it up.

Had similar issue here a few months ago.

How to move a Microsoft Exchange mailbox for a BlackBerry smartphone user
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Tried this once, it worked. Then user wiped handheld to clear some data and we tried again, even after moving the mailbox back and forth to the secondary database with the user off the enterprise manager he is having the same issue again. Any other thoughts?