game crashin in the editor.

[Rex Lupus]

when I try to acess the in game editor (I don't know how it's called) the game crashes. when I click in create new map (where it should list the maps I have saved and an option to create a new one) the game freezes. someone knows what could be the problem?
I've already try to verify the game cache.
sory for the bad English, steam doesn't have the dictionary that chrome has.