I've seen this a million times in peoples outlook calendars here at my 9-5.

This generally happens when the "automatically adjust for Daylight Savings time" is out of sync between the user's comptuer and the server. (In this case, the server is probbaly set to use UTC and a NTP time server)

Unfortunately, the easiest fix for us is to change the setting on the client 's computer and fix the borked appointments. Read the source page for Microsoft's offical fix.