Hello, all.  I had previously posted about this topic, but now have narrowed the problem down a lot.  I submitted a bug to Mitel, but have gotten no suggestions.
I'm running an unmodified 5.6 install with the latest updates. 
The problem is that every time I run an action that uses usermod -G the usermod process goes to 99% cpu and stays there until I kill the process. 
Has anyone else had this problem, or can anyone suggest some way to troubleshoot this problem?  It looks a lot like the old groups bug which was reported as fixed in update two.
I'd love to hear any suggestions to try. 
Thank you,
Kirk