blocked web pages

i downloaded and installed recent updates for XP home [with sp2 already
installed]. now, i am not able to access any of the web pages where secure
information is stored. for example, i can't login to my ebay account. i get
a no-such-address message when i try to go to paypal.com. i can't access the
login pages for my banks and credit cards. i get the "unable to connect,
server might be down" message. i can browse the internet, i just can't
access high-security pages. i use a wireless broadband router for one laptop.

i tried restoring to an earlier time, but no luck. i tried re-setting
internet options for privacy, security, etc.

anyone have a clue as to what the problem might be? i don't know if it's IE
or XP. i tried using firefox as a browser and the same thing happens -- not
able to make a connection message when i attempt to go to a login page, which
makes me think it's an XP problem.