[ENT-421] This is caused when a non-existant gorup is referenced, not a typical occurance.  That said, the user of the error page is improved a bit.

git-svn-id: http://svn.igniterealtime.org/svn/repos/openfire/branches/openfire_3_5_0@10127 b35dd754-fafc-0310-a699-88a17e54d16e