Changing your MAC via TMAC will cause the IW_22.IWD to become corrupt and thus keeping you from online play.
My guess is that the server used the temp ban client command that only bans for 5 minutes and while you were working on a way to evade the ban expired..
Also, I wonder if the error didn't show because there was another valid adapter to generate it off.. there has been some code changes on that part so I'm not 100% sure.
MAC changing programs and changing it in the registry wont change XUID.