What raid size should be "stable"?

[Yeormom]

Like Derision said, it's a problem in the code. Applying updates is probably a good idea but you could attach a debugger to your zone file and catch the exception that way as it is most likely one little thing that keeps getting triggered. There's always the one odd case that rarely occurs like a person trying to invite a charmed npc to the group and it tries to process the request because of some past modification.