I have a user who has a recurring meeting on her Outlook 2007 calendar (actually it's an all staff meeting so pretty much everyone in my company has it). However, when she tries to open ANY instance of this recurring meeting, she gets a pop up box saying: "Cannot open this item. The operation failed. The object cannot be found". I get the error as well if I access her calendar, so it can't be related to the PC itself (I already tried deleting the frmcache.dat files and realized since I cannot open it either, it's probably not that).
The most annoying part is that she keeps getting reminders for the most recent meeting (they happen weekly) and it won't allow her to decline it.