WF 3.0.1 errors

We are getting these errors constantly through out the logs. Can any one shed light on what might be happening? We are using AD for ldap.

2006.12.07 12:46:36 [org.jivesoftware.wildfire.roster.Roster.(Roster.java:161)] Groups () include non-existent username (cn=agt_xxx_xxx,ou=groups,ou=xxx,ou=canada,dc=noamer,dc=domain,dc=com)

Message was edited by: Tyson