Active Filter in Groups/Latest Discussion

I installed ELGG 1.5 on April 1st and changed a PhPNuke site to a ELGG site (www.stxsoccer.com)

The transition has gone very well, and over 500 users already made the switch.  First big glitch today.  For some reason, when you go to main groups page:

http://www.stxsoccer.com/elgg/pg/groups/world/

and click on Latest Discussion

http://www.stxsoccer.com/elgg/pg/groups/world/?filter=active

it simply returns a blank page.  I have not made any changes to any code since installation and this was working fine a day ago.

Any ideas???