What version of Messenger are you using ? (Help > About Messenger)
What filewall are you using? (Ex. Zone Alarm, McAffee, etc.)
There doesn't seem to be a fix for it, but you can try these steps...
Also, you might want to contact Microsoft about it (link at bottom of page).
quote:
"Since you can't immediately login, remember that you can try logging into the Web Messenger, at least until you can restore your normal Messenger functionality: http://webmessenger.msn.com
However, here are some suggestions you should check/try if you haven't already.
1. The date on your computer needs to be set properly -- double click the clock verify that the time and date are set.
2. If your password information is not saved, verify that you are typing it in with the correct case (uppercase or lowercase).
3. Change your password @ https://login.passport.com/ChangePW.srf to something smaller (under 10-12 characters), then try signing in again.
4. If you use a firewall (like ZoneAlarm, Norton Internet Security etc. ), it's possible that Messenger doesn't have the correct rights to access the Internet, especially since you upgraded. You may need to re/add Messenger to the allowed list of programs in your firewall if this is the case.
5. If you disabled your firewall in the past, it still may be blocking Messenger -- try restarting it and see if that helps the situation. You also might try uninstalling an installed firewall, to verify that it isn't causing a problem (even if it is disabled).
6. Clear your IE cache and cookies -- open Internet Explorer, click the Tools menu, then Internet Options, then click the Delete Files button, and when that's complete click the Delete Cookies button.
7. Check your IE Security settings -- open Internet Explorer, click the Tools menu, then Internet Options, then Advanced tab, scroll to the Security section, and verify that "Check for server certificate revocation" is unchecked. lso verify that 'Use SSL 2.0' and Use SSL 3.0' is checked, then click OK.
8. Click Start, then Run, and enter the following:
regsvr32 softpub.dll
then click OK
and do the same for the following:
regsvr32 wintrust.dll
regsvr32 initpki.dll
regsvr32 MSXML3.dll
____________________________________________
Jonathan Kay
Microsoft MVP - MSN Messenger/Windows Messenger
Associate Expert
http://www.microsoft.com/windowsxp/expertzone/
Messenger Resources - http://messenger.jonathankay.com
All posts unless otherwise specified are 
2005 Jonathan Kay.
You *must* contact me for redistribution rights."
quote:
Given what you've indicated, there may be a specific problem with your account. You may want
to escalate this to Messenger support so that it can be sent to the correct people.
http://support.msn.com/contactus.aspx?productkey=messenger
/ 
