Did XP-ServPak 2 - IE won't accept home page

I just updated with the Windows XP Service Pak 2. I use a "my.yahoo" site for my home page. When I log on, the browser takes me to "Yahoo" and I am asked to log on with ID and password. When I do so, I receive a message that my browser is refusing access.

I've changed a few things (even if only temporary) on my "Privacy" setting on IE to see if that would allow me access - but it doesn't.

Can anyone provide some help? Surely the problem as to do with the installation of the XP service pack.

Thanks