this error keeps showing up on my first primary server and when it occurs my users cannot log into their workstations.

Full Message:

The assignment web service encountered the following exception while handling "getEffectiveAssignments" request for 2542dc82e78ce518b81efd50c2b4760c~006667bb31b3e011a 86000151743d7f7: javax.naming.CommunicationException: connection closed [Root exception is connection closed]; remaining name ''

ZCM 11 SP1 on SUSE
eDirectory user source
Clientless login
DB SQL 2008R2
user are student with volatile account who are free log into any of the workstations provided for them