Seen a couple of other people post about this error code 81000306 when
trying to logon to messenger on Vista and no solutions so far.
Have done lots of testing, running the Web Based Messenger works ok. Seems
to be some kind of firewall issue. But I still get the problem with Windows
Defender and Windows Firewall disabled.
Also tried Safe Mode with Network and get the same error.
Other IM applications like Skype, Google Talk work perfectly.
Windows Live Messenger worked on this PC with XP and still works for other
machines on the network.

Help, completely stumped on this one.

I had this problem and your symptoms sound pretty much identical to mine. I
found the procedure below in another group, and it solved the problem for me
and at least a couple of other people that I know of. Apparently Vista's
"auto-tuning" networking
feature doesn't play nice with some routers. Not sure if it is a bug in
Vista, a bug in Messenger or a bug in the router firmware.

Try this:
- Click start
- Type: cmd
- Right-click cmd.exe when it appears under Applications
- Click Run As Administrator
- Type the following: netsh int tcp set global autotuninglevel=disabled
- Press enter
- Restart your computer

Regards,
David

Thanks David,
Just found that fix in the same group you did I think. Wish I had seen it a
week ago :-)

"David McGown" <dmcgown_NOSPAM********.com> wrote in message
news:58451E18-FF3F-4799-B306-C05549C93B2D@microsoft.com...
>I had this problem and your symptoms sound pretty much identical to mine. I
>found the procedure below in another group, and it solved the problem for
>me and at least a couple of other people that I know of. Apparently Vista's
>"auto-tuning" networking
> feature doesn't play nice with some routers. Not sure if it is a bug in
> Vista, a bug in Messenger or a bug in the router firmware.
>
> Try this:
> - Click start
> - Type: cmd
> - Right-click cmd.exe when it appears under Applications
> - Click Run As Administrator
> - Type the following: netsh int tcp set global autotuninglevel=disabled
> - Press enter
> - Restart your computer
>
> Regards,
> David