Outlook 2000 not checking for new mail

Configuration:
Outlook 2000 in Coporate/Workgroup Mode on multiple WinXP LAN clients. Each uses 1-2 internet mail accounts and 1 MS Mail account.

Symptom:
Intermittently, the Outlook client will simply stop checking its internet mail account(s). I’ve logged a couple of stations exhibiting the condition, the POP log just stops when the client stops checking for mail, no error logged. The MS Mail service continues normally.

Workaround:
Closing Outlook and reopening it will bring in the new messages.

This is happening itmermittenly throughout the building, with no pattern I’ve yet to discern. Any help would be appreciated.