I have a customer that uses their calendar for service scheduling. So they have around a dozen appointments on every  day during the week on a shared calendar amongst five users. They have appointments as far out as three months and keep past appointments for one year using the auto clean feature for the calendar set to 12 months.

 

A couple days ago they came into work and all of their appointments were missing from the calendar. Not one single appointment was on the calendar. I replaced the XML file for each user that had write privileges to the calendar from a backup and still no appointments show up.

 

I was able to make new appointments with no problem and they stay on the calendar from one day to the next. Any ideas on how to find out what happened so it does not happen again. If by chance a user deleted all the appointments in the calendar, is their a log file that can be looked at for that? They say no one would go through all the steps to delete all the calendar appointments. And only two users have write/delete access. All the rest are read only.