I had this happen once when I needed to adjust the time on the PBX, The Symposium gets it time off of the PBX and when I adjusted the time on the PBX Symposium freaked out because it showed agents logged in at say, 3pm and then all of a sudden it was 3:04 and it couldn't account for the lost time, so it started randomly re-logging agents in, and in some cases it would do this several hours after the business had closed.
Everything cleared up after a day or two but that weeks reports we're hosed.