Windows Help Center behind a proxy

I am working on Windows Vista Business. To access the internet, I have to go
through a proxy server that requires authentication. I have specified the
required proxy settings in IE and whenever I run IE, it prompts me for
username and password.

On such a system, whenever I open Windows Help and Support Center, it cannot
access online help and doesn't even prompt me for authentication. It can only
show offline help. please suggest how to resolve this.....

Note::: as a peculiar thing, on the same system, windows update works
fine.....whenever i run it, it prompts me for proxy details and subsequently
downloads stuff....

Thnx!!!