Start by uninstall Messenger Plus! to make sure that isn't the culprint.
Next, try to enter the following command:
1) make sure all the Messenger processes are closed
Close Messenger and check your Task Manager (Ctrl-Alt-Del) for any running Messenger processes. If there are still processes running, kill them
2) click on your Windows Start button
3) Choose "Run"
4) type (without the quotes): "ipconfig /flushdns" and press enter
5) try to restart Messenger and sign in.
If you still experience errors after that, you should report them to Windows Live Support:
http://support.live.com/eform.aspx?productKey=wlm...&ct=eformts&scrx=1
/ 
