I had the same thing happening to me four or five days ago, but I wasn't doing anything but chatting with two people. I opened the main window and my list appeared that way. It was indeed very strange... I shut down MSN, opened it again, and everything was fine again. No further problems since then.
Didn't look like a Plus! problem to me... rather some serverside problem at Microsoft. But I don't really know.
/ 
