i recommend you run this software
http://www.superantispyware.com/
Get the free version update it and run it on full scan (make sure you have no programs running)<<V important
This will remove any MALWARE that you might have on your pc that might cause these types of pages not to load
If you can, cable your internet straight to your PC so you can see if it is a router/modem/firewall problem so we can eliminate it
Theres soooooooo many variables on why you cant view HTTPS we need to start eliminating them
You wont be able to access "local security policys" because XP home is too basic
Disable all your firewalls (Windows and any others you might have loaded and stop any security you have running)
I think if you cable your internet straight to your PC it will work, did you try opening port 443?
If you have MSN i can do remote assistance its a lot easier to diagnose the problem this way....
Also do you get a certificate page load when trying to visit these pages? OR does it timeout?
let me know thanks