Are you using msgplus with plugins? If so, disable plug-ins and try again. Especially the stuffplug plug-in. If it doesn't even let you reach the plug-in disable screen,
D:\Program Files\MessengerPlus! 3\Plugins and cut the dll files from there, put it in some other folder.
Where D: is your drive name of course;)
If it isn't msgplus, remove any other msn patch you have applied, then do a complete re-install. If that doesn't work, your only alternative might be reverting to MSN 7.0