Board Thread:Bug Reports/@comment-83.134.96.155-20141030125527/@comment-27723099-20141030131205

With 'window' you mean a GUI such as the inventory or a crafting table, I guess?

The crash report did not name the mod as crash source (what kind of window was it?) but you have insane amounts of uruks/orcs loaded (I counted 115 in total!!!). Try to lower your render distance or try if you can open (modded) windows in the overworld.