I have the EXACT SAME PROBLEM, but ONLY with my Yahoo mail since that´s the service I use.
It started when I tried to run an old application and it ran afoul, causing my PC to crash, after which I couldn´t restart. So I had to uninstall that software while in safemode because there was no way to enter normal mode.
Even then, I still had trouble opening Windows. It was restarting before it finished opening. So in the msconfig START panel, I cancelled most pre-loading software except the Norton Internet Security and AntiVirus.
Only then was I able to reenter my user profile, and use EVERYTHING EXCEPT YAHOO MAIL.
I know it´s something to do with the Norton Internet Security, and it´s firewall, because it´s trying but failng to reinstall some "missing" thing.
The ONLY PAGES I can´t load are ALL THE LOGIN PAGES, for Yahoo, but maybe also for other services. YES... Just tried gmail and can´t get a sign-in page. It must have to do with the secure pages. I don´t see the "pad-lock" come out on any page anymore.
I´ve tried but can´t reconfigure my Norton NIS. I just get the main panel but can´t change any settings. Somehow it must be "stuck" and just in case it disables secure/encripted pages.
But I can´t take the risk of uninstalling it now, because I might ruin my entire system, and hardrive and I don´t have time yet to BACKUP ALL my data.
Capt Dave´s idea sounds the best for now.
You SHOULDN´T TRY to uninstall or install anything now until YOU BACKUP ALL your valuable-irreplaceable info-files.
ONLY THEN should you try to fix it, because if all else fails you will need to RE-INSTALL THE ENTIRE HARDDRIVE.
This is basically required after every 2-5 years anyway depending on how much you use your notebook, because it all just gets too clogged up. Just another basic flaw of the opertating system.
(probably to sell more PC´s-OS´s because people forget how FAST their old PC was when they just began using it)