I have a few users (about 7 of 400) where their emails are disappearing intermittently on outlook, the emails are however still on OWA in the correct folders.
After running the following Shell command in exchange and restarting outlook everything works fine again for about a week.
[PS] C:\Windows\system32>set-mailboxcalendarsettings email@example.com - AutomateProcessing:autoupdate
Then for some odd reason AutoUpdate changes to AutoAccept and the problem starts again.
They are all using office 2007 with SP3 but I suspect the problem is on exchange and not on the local machine.