Windows xp https blocked

[wh747]

Hello, I am unable to tell why https sites are blocked, specifically gmail and yahoo mail. winxp home acer aspire one. i cannot tell what software cahnge3 may have precipitated this. CAN access gmail in safe networking mode.

 

[PhilFrisbie]

Did you try another browser? Have you updated any security software?

 

[wh747]

Browser: Recently updated Firefox (V 14 or 15?). Disable all add-ons to try to get it to work. Nothing.

Windows IE 7: Same thing. for example, can get to Google, but cannot get to gmail.

Have been using AVG and MalwareBytes on all my laptops for some time. Disabled both programs to see what would happen. Nothing. Same problem. Did a system reset back to a date when computer was working fine. No change. Still no gmail or yahoo mail. Update of Win Home - no change. I did not detect anything grossly suspicious with Windows Task manager, but I am no pro at that either.

I regularly scan by AVG with up to date database, malwarebytes and Spybot Search and Destroy. Showed computer clean.

I had to give up. Left the computer home and took another on a trip.

Computer pros who have done IT work at my office said my computers are generally quite clean (6-computer LAN on a XP domain server with wifi access by max of 3 laptops, all 3 are known to me. Though that means next to nothing re: rootkits, viruses, trojans, etc. of which I have virtually no working knowledge except to use whatever tools I can, to try to scan for them and to try to keep them out.

Part of me wants an answer. The other part says I cannot afford to waste too much time. I am going to do a reinstall of the OS (A real pain) if I cannot find a workable answer in reasonable time 9back in the office end of next week). I misplaced the XP Home restore discs for the computer, so will use the office XP Pro install disk (It is my company and I own the disc), as I need to have domain access anyway. On the off chance that there is some rootkit or virus lurking in the office system (all other computers seem to be running fine), is there another anti virus that is better at digging out obscure ones, than AVG, Malwarebytes, and Spybot S&D?

Thanks.