Odd Group Problem

On my elgg install I am running 1.5 All standard code

This morning I went to one of my groups - Clicked on Group Discussion and got a blank Page

This was a 1st. 

Decided to do some checking

I have a total of 10 groups on my install

9 of the groups allow me to goto the group discussion tab with no problem.

The other 1 just gives me a blank page.

There is nothing special or different in the group from the other group?

Any idea what could be causing this or what I can do to fix this?