x80072F76 error when doing windows update.

I get the above error code when trying to perform a windows update.

I do not have any firewall on my machine and connect to the internet through
a proxy server. This is the only way i can connect to the internet.

We go through a pix firewall, and all worked ok witht he old version of
windows update v4 only the new one is causing these issues v5.

Please can some body help. I have tried all the solutions posted so far but
non of then work.

Thanks