Edit recipients groups returns 500 error

Hello All

I started having a strange error today on my Exchange 2013 ECP.  When i go in to edit a group under recipient --> groups and select a group and hit edit, i'm getting a 500 Unexpected error message after about 5 minutes trying to open the page.  I get this from the localhost/ecp as well.  So far this is the only page that i get the error on.  I've restated IIS on all the servers tried different computers / browsers but nothing seems to work.

Anyone have any ideas?

Thanks in advance for your help

-Chris