I hope you are talking about Windows Live Messenger 8, which is the replacement for the old MSN Messenger (which no longer works with Vista.) You have done all the troubleshooting steps, you say. Which are these? Have you seen this page:
http://www.techsupportforum.com/mic...ows-live-messenger-8-connection-problems.html
Here is a quotation from someone named Zazula from the above page:
First of all, repair Windows Live Messenger:
1. In the notification area on the taskbar (near the clock), click the Messenger icon, and then click Exit.
2. On the taskbar, click Start, and then click Control Panel.
3. Double-click Add or Remove Programs.
4. Under Currently installed programs, click Windows Live Messenger, and then click Change.
5. Click Repair.
Next, check your Messenger connection settings:
1. Launch Windows Live Messenger.
2. On the Tools menu, click Options.
3. Under Connection, click Advanced Settings.
4. In the Settings dialog box, click Test in the HTTP section. When the test results appear in the Connection Tester dialog box, click OK.
5. Click OK, and then click OK again.
6. Use the test results to determine which settings are causing the connection issue. Post back the findings (if any) to be specifically advised.
After that, check your firewall settings:
1. Visit the MSN Web Messenger website.
2. Click Start MSN Web Messenger, and then try to sign in.
3. If you can sign in to MSN Web Messenger, Messenger may be blocked by a firewall.
4. If your computer is running firewall software, make sure that the software is set to allow Messenger to operate, and then try to sign in to Messenger again.
Then, clear the Windows Live Messenger proxy settings:
1. Launch Windows Live Messenger.
2. On the Tools menu, click Options.
3.Under Connection, click Advanced Settings.
4. Under SOCKS, delete the entries.
5. Click OK, and then click OK again.
Lastly, adjust the Windows Internet Explorer proxy settings:
1. Start Internet Explorer.
2. On the Tools menu, click Internet Options.
3. On the Connections tab, click LAN Settings.
4. Clear the Automatically detect settings check box.
5. Click OK, and then click OK again.