it happens to me sometimes, never understood why. I got to reboot msn to get the normal display back..
(!VER) : win xp he
msnmsgr 6.2.0137
msgplus 3.01.0094
display drivers : nvidia forceware 61.77 (hm, i made the update a few days ago, can't remember if i met the bug since then..)
/ 
