Okay, so it is all kind of cloudy, but I remember some kind of big monster/man (possibly a robot?? ) who roams around making everything turn gray. And, there was an artist who did something. And in the end, the big thing is defeated and I think it might have turned into a clown and there was a color explosion. I think. Also, the only vivid memory I have is mushrooms dancing around singing the lyrics to Pink Floyd's "Another Brick in the Wall" which is really weird... HELP!! It has been driving me crazy for years!! :confused:

Could be The Elm-Chanted Forest (http://www.imdb.com/title/tt0268282/) from 1986.