Exchange Recurring Appointments Problem

We have users that have recurring appointments setup. All of a sudden they can’t access the appointments. If you look at the calender on the days the appt are scheduled, they are bold, but when you click on the day nothing is there. If you try to re-setup a recurring appt Outlook claims it would conflict with an existing appt. We roled back a user’s PST and it did nothing but remove the appts and the bolded days all together. Any help would be appreciated.
Thanks