i had the same problem, but only when I signed in and tried to open a conversation window, so I tried MSN 6.2 and the problem remained, so I disabled File Transfer Plus plugin and the problem was gone. Just to check if that was really the problem, I re-enabled the plugin and yes, the problem was back again, so I decided to remove File Transfer plus. it might be just a coincidence but it worked for me. too bad I had to stop using File transfer plus though
I am using MSN Messenger 7.0.813 and MsgPlus 3.52.130