Need help with Slingbox remote access, please

Hi --

Sorry for the crosspost. Just realized that my original posting was to the
wrong group.

The situation is that I have a new HP DV4T with Vista 64 bit and a new
Slingbox Pro-HD and am having trouble making the HP DV4T cooperate.

The Slingbox is configured to use Port 443. (Had no luck with the
recommended 5001 port.) Have forwarded 443 both for TCP and UDP.

I believe the Slingbox configuration is correct because it works as it
should with the Vista 64 computer on my home network and I am also able to
do the remote access from my work desktop that uses XP Pro.

The problem exists only with the Vista 64 computer when attempting remote
access.

Have tried totally disabling the Windows Firewall and totally disabling
Norton 360. Have "trusted" everything on my work network where I am
attempting this from. (It is not a question of a Network Administrator
blocking some ports because I would be the only one to configure such.)

Have allowed Ports 443 TCP and UDP on the firewall.

Still no joy.

Can anyone suggest what I am overlooking?

Thanks.

Zan