Can you try the following:
Uninstall Messenger Plus!, and also any other addon you might have installed (eg: Smiley Central, etc).
Uninstall the beta version of Windows Live Messenger (in case you have it installed), and install the latest version again.
Then proceed to the following page and follow the instructions exactly:
http://windowslivehelp.com/solution.aspx?solution...-8671-8b44fe19383b
this is to remove the contacts cache. If Messenger crashes after signing in, it could indicate a faulty cache.
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