Shamelessly ripped from Slipstick: (thanks, guys)

If your Outlook seems possessed and turns all of your meeting requests into recurring meetings, you have a Dell laptop with MediaDirect.

There is a bug in the add-in that reads Outlook meetings so Media Direct’s Instant Office can display then without fully booting into Windows. You’ll need to uninstall it, or disable the add-in called “Outlook Setup Addin (Cyberlink)” to put an end to the errant recurring meetings.

Original post here:
http://www.slipstick.com/problems/recurringmeetings.htm