you will see this in your screen :
"Sorry, we are unable to sign you into the .NET Messenger service at this time. Please try again later."
"Sorry, we were unable to sign you in to the MSN Messenger at this time. Please try again later. MSN Messenger has made several failed attempts to sign you in. Your firewall may be blocking Messenger from connecting to the service. Please review your firewall settings. See the retailer's instructions for more information."
The possible causes this problems are :
1) Firewall settings
2) Security settings
3) MSN proxy settings
4) your clock and date setting may be showing incorrently.
SOLUTIONS:
1) Launch Internet Explorer, click "Tools" and then click Internet Options.
From the Internet Options dialog box, go to the Connections tab.
Click LAN Setting.
Un check the Use a proxy server for your LAN (These settings will not apply to dial-up or VPN connections) checkbox.
Finally positively tick: 'Automatically detect settings'.
2) Register softpub.dll.Click Start (Button), and then click Run, type regsvr32 softpub.dll. Restart MSN Messenger.
3) If necessary, logon as a local administrator, set the computer's clock to the correct date and time. (Check on the internet if possible.)
4) Turn off the firewall temporarily.
Check firewall settings such as Norton: "Block access to secure sites".
If this cures the problem, make sure that Microsoft's MSN Messenger is allowed full access through your firewall.
Source: msn-errors.blogspot.com
Hope it's useful to you! =)
