Its M$ fault. happens because your contact list doesn't sync with M$ servers properly.
There away to delete your locally stored contacts list (could be corrupted) cookie kno's what to do, because he posted it few places. i stole it **ahem** posted it around different places. cant find it now thou.
like you delete msn folders in in documents and settings. and stuff. bit tired and sick at the min, so maybe i'll check how to do it for you tomorrow
/ –
