Against invisible Opponents you lose your Dex Modifier. I assume that you cannot make an Attack of Oppertunity when you lost your Dex Modifier, so in this special case you may not make any AOOs against the Invisible guy.
Well, the interesting question really is - Can I get an AOO at all? (Even if I have to guess the field and take the 50% Miss Chance) With Combat Reflexes, I might allow it ...