Ichat Facebook Password Incorrect [Extra Quality]
I had same problem repeatedly. When I looked into the Jabber keychain attributes, I selected "show password" and saw that the stored password was incorrect... a very old password that I had used on that account a few years ago. I manually updated it to use the current correct password, and now the problem seems to have disappeared. It seems that the password that I had been typing upon launching Messages app in wasn't being written to the keychain, so at least manually updating the password works around the problem.
ichat facebook password incorrect