Somehow doing this ended up stopping Windows Live Messenger 8.1 from being able to login.

A lot of searching revealed that there are some known issues between Windows Vista and certain Routers. This has something to do with the way in which Windows Vista’s new networking stack can tune itself for the best performance. You can read more about the auto-tuning feature in this column on Microsoft’s website.

The easiest and best solution I found was to downgrade my router’s firmware back to version 3.01.25. I have been running this version successfully with no network issues at all for weeks now.

You can find Netgear firmware downloads at http://kbserver.netgear.com/downloads_support.asp. Consult your router’s manual for installation instructions.

If this doesn’t work for you, you’re already using that firmware, or you have a different model router, then you can try disabling the “Autotuning” feature:

1. Click Start and type “cmd” into the Quick Search box.
2. Right-click the “cmd” item that appears and select “Run as administrator” (Or hit ctrl+shift+enter). Click “Continue” in the resulting UAC dialog and a Command Prompt window will open.
3. In this window type the following string:
   netsh interface tcp set global autotuninglevel=disabled
   and hit enter. The prompt will return “Ok.” If successful.
4. Close the command prompt by typing “exit” then enter, or by clicking the close button in the top right corner.
5. Reboot your computer.

I found that disabling auto-tuning worked great for restoring Windows Live Messenger functionality but I was still experiencing some random network issues. Try the router firmware option first if you’re able to.

If you’re using a “current model” ADSL Modem/Router then continue to keep an eye on the manufacturer’s site for an updated, Windows Vista compatible firmware version.