You must have me confused with someone else.
1. You must have me confused with someone else.
2. You must have confused me with someone else.
Some say the problem in question is nothing but tense: The first means "You are mistaking me with others" while the second "You were~".
But, what I really wonder is that doesn't the 'confused' in the first take the roles of adjective? I get the whole sentence's meaning, but when I see the 'confused' part only, it seems to be ungrammatical, since the 'me' is the one who's confusing.