So far the diagnosis for these symptoms; It seems to be occurring when an incompatible skin is used with Windows Live Messenger 2011.
Please try switching to the default skin or find a skin compatible for Windows Live Messenger 2011. On top of that, you could also consider using Windows Live Messenger 2009 instead.
In the skins database you can search for skins by compatibility, by selecting "Live Messenger 2011" in the "Version" drop-down menu and pressing the Search button.
Also note the details next to each skin preview thumbnail.
Note: This may not be the sole cause for these symptoms.