Generate Organization Certificate

PGP Universal Server 3.1.2

My Organization Certificate expired a few weeks ago and since then, users keys have stopped renewing.  Is this related? 

How do I generate a new Organization Certificate?  Instructions I've been able to find are not clear. 

I'm new to PGP Universal Server, and before I go in and make changes to the production server and really muck things up, is there anyone that can give some guidance?

We don't encrype email, so S/MIME is not a consideration.  Will a self signed certificate be adequate, or should I get a CA certificate? 

Thanks in advance.