One of my Windows Live Messenger installations stop working recently and I spent quite a bit of time trying to repair it. The standard procedure is to uninstall through the Control Panel and then reinstall, but this didnâ€™t work and I kept getting the same error. The application would crash as soon as I would login.
I searched the Internet and tried many solutions, but nothing worked. Fortunately, Microsoft posted a solution which details a thorough uninstall of Windows Live Messenger. It involves executing commands from Start->Run and also running commands which delete entries from the registry. The instructions are easy to follow, but may be somewhat intimidating for a novice user.
After following these procedures, I was able to reinstall a working copy of Windows Live Messenger. This page can be found at Clean Installation of Windows Live Messenger.