Comments Won't Turn On

It does not matter how the discussion settings are configured, I cannot turn comments on at any network blogs. At first I thought the problem could be with Ultimate facebook overriding the settings but even with Ultimate FB deactivated the problem is still apparent.

Something somewhere must be over-riding the settings because I cannot turn comments on at any network blogs. I've tried deactivating the network activated plugins one by one and still a comment box will not appear on any post of any networked site.

Anyone any ideas?