Earlier today i spent about two hours to fix the WLM Automatic sign in issue. The problem started to appear after i upgraded my Internet Explorer 6 to Internet Explorer 8 downloaded from Yahoo Website. I reinstalled both Internet Explorer 8 and Windows Live Messenger but nothing worked out.
However Luckily I found a fix for it. This problem possibly could be because of Yahoo Toolbar making certain changes in the Reigstry, and somehow Windows Live messenger (WLM) is no longer able to remember password and sign-in automatically once you start your computer, and it is too annoying to enter your login and password every time you restart the computer.
However the Fix that i found here, is very simply. Just Download this file in zip, Extract it and Run the file. Once you run this file it would automatically restart your computer so to make sure to save your work before running this file. And Once the computer restarts the problem is gone and you would notice your Messenger signing in automatically the next time you restart the computer. You might need to enter your login for once after running this file however after that it would keep remembering your sign-in details.

Long time ago I had stopped using MSN, I use jabber or gtalk now
Thanks! my Messenger is now signing in Automatically again, it stopped signing in after i updated my Yahoo toolbar. Cheers Geoff…
You are welcome Geoff