How to Fix the Windows Live Messenger Unable to Sign In Error in Vista

ERROR MESSAGE: We were unable to sign you in to Windows Live Messenger, possibly because of a problem with the service of with your internet connections. Please make sure you are connected to the Internet. Error code 81000306. WHY: Vista's TCP Auto Tuning networking doesn't work well with some routers or other network devices. Thus, causing a connection error for Windows Live Messenger.
NOTE: Make sure that you have the latest released version of Windows Live Messenger installed to help avoid having problems. See: Windows Live Suite Downloads
NOTE: Make sure you have your firewall program setup to allow Windows Live Messenger (msnmsgr.exe) In and Out access to the internet. If this doesn't solve the problem, then continue. If your using Windows Firewall, see: How to Change Windows Firewall Settings in Vista

1. Open the Start Menu.
2. In the white line (Start Search) area, type cmd.
3. Right click cmd (At top) and click Run as administrator. (See screenshot below)
cmd_Start_Menu.jpg
4. Click the Continue button for the UAC prompt.
5. In command prompt, type:
netsh int tcp set global autotuninglevel=disabled
NOTE: To undo this, type:
netsh int tcp set global autotuninglevel=normal instead.
6. Press Enter. (See screenshot below)
7. You will get a OK message back. If not, repeat step 4.
Disable.jpg
8. Logoff and logon, or restart your computer to apply the changes.