Microsoft support for XP has ended so SSL certificates will expire and other issues predominantly with Internet access will start to fail with messages like "Invalid Or Expired Security Certificate" therefore:
Very quickly...
1. Without IE your 3rd party browsers would simply not work in Windows so upgrade IE even though you may not be using it to version 8 from here:
http://www.microsoft.com/en-us/download ... tails.aspx
2. Install Windows SP3 if you're still on SP2. Restart at the end.
http://www.microsoft.com/en-us/download ... aspx?id=24
3. Use IE8 (only) and log onto this site:
http://www.update.microsoft.com/windows ... e&ln=en-us
Now select CUSTOM and "scan/Install" any security updates offered.
NB:1 If a "Root Certificates update" and/or KB971029 is listed in the "Optional Software updates" category on the left-hand side
of the scan results window, install them.
NB:2 Don't install any other optional software updates nor hardware updates.
That's it.
Once you've checked that you can now access all sites alright you can now go back and turn off the windows update, firewall, error reporting service, etc, and anything else you had turned off before the problems began.
Bye!