Redownload editor, and try installing it again, maybe in another location.

marklv, are you sure, that you're getting the same error as roman1uk? Can you post here all exception text you get?

It seems that something is blocking your scenario files. Try one of this solutions: - Make sure that you don't have any programs running in the background (especially game) - Restart your computer and try to load this scenario again. - If you have Windows Vista/7, run editor with administrator privi...