I'm using MSN Messenger 7.5.0299 MsgPlus 3.54.132.
A few days ago, a friend of mine tried to sign in into his account in my computer, but it didn't work, Messenger showed error #80004005 and wouldn't sign in (only happened with his account).
Now I was trying to find out what was going on, so I closed MsgPlus and ran Messenger and this time it worked. I tried again with MsgPlus running and it didn't work. Then I noticed that the e-mail address in Messenger's main window changed to the custom nick I had set in my account! I disabled the custom nick feature in my account and voila, my friend's account works again.
Try to fix it for tomorrow, Patch.
EDIT: changed subject, sounded crappy