When user accounts are added to Active Directory security groups, they are not added to associated groups in Encryption Management Server.
In the Encryption Management Server administration console under Reporting / Logs / Groups log you see multiple occurrences of this error:
USERQUEUE: Unhandled exception: std::bad_alloc
Symantec Encryption Management Server 3.4.2 and above.
The pgpgroupd regrouping service has stopped working.
Restart the regrouping service from the administration console by going to System / General Settings and clicking on the Restart Services button.