It should be closing the matchmaking error when ever it appears, if it doesn't get it by the time the host has to invite it waits for it. When does yours pop up?
Are u finding by name? It shouldn't quit autoit without bringing up an error. You haven't changed the name of the diablo windows? You running as admin? Are the windows sized right? Did u make windowed, close diablo and copy my d3prefs to yours?