Could you tell me the error code you get?
Have you got any add-ons for Messenger? If so,
see here.
Do you have a firewall?
quote:
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. [Source]
Either that or disable it, then try.
Researching on Google, a
couple people have said that using a different Windows account may fix the problem. You may want to try that.
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