If you already updated your flash player aswell then the best thing you can do is do a fresh install of everything.
1. Follow all instructions (point 1 to 9) provided in
Completely remove (MSN/Windows Live) Messenger
2. Redownload and install the latest WLM (8.1.0178) at
http://get.live.com/messenger/overview
3. Redownload and install latest Plus!Live from
http://www.msgpluslive.net/download/
4. Test it..
5. Redownload and install A-Patch
Edit: see my last post first....sorry i didn't think of that one first...
/ 
