Last weekend we upgraded to GW7 SP1 and Messenger 2. Yesterday and this
morning we upgraded the clients on the workstations. As we got to the
last few people we suddenly had users reporting that their contacts list
had disappeared? We checked the settings of the user used by the
Messenger agents, confirmed password etc, and rebooted both agents
(messenger and archiving). Users started connecting and contact lists
reappeared. After about 30 minutes though the same problem appeared again.

Any ideas?