This is really odd.
So you only have Windows Live Messenger & MessengerPlus! Live right? No other add-ins/plugins (like StuffPlug 3, MessengerDiscovery X, Messenger:Mate etc.), patches (like MessPatch, A-Patch etc), skins?
Also, what version of Windows Live Messenger do you have? You using 8.1.0178 as Sunshine suggested above.
Sorry if this has been asked before. This is a really strange problem, which must be caused by something.
~Salem