Weird outlook/exchange 2003 issue: calendar items randomly get deleted

[Red Squirrel]

It's been reported to me that calendar items are getting deleted randomly. From my understanding it's only one user, but hard to tell as I do not have first hand experience with the issue and have not seen it happen.

Basically the user will accept a calendar appointment, it goes in their calendar, then later down the line the item will no longer be there. They are confident it was not deleted.

We also have a BES environment and that user does have a blackberry, so maybe it has to do with something BES related.

Where do I start looking as far as logs go? I tried to track a particular one in exchange but it errors out saying it can't load the log info because the item has been deleted. Kinda defeats the purpose of logging... The BB logs don't have enough detailed information, so it's hard to tell what messages it's referring to.

Also we have another issue that we gave up on, but just in case it's somehow related, this is the thread: http://hardforum.com/showthread.php?t=1550055

I am hoping we get the green light to upgrade to 2008, maybe all our problems will go away if we're lucky.

Any help would be appreciated, thanks!