This is a fairly complicated story that I will not be able to entirely share with you right now (it would take too long). But I suspect a virus problem is at the root. I will be glad to fill you in as you have questions. I have conferred with my fellow IT Admins and they agree. They have made a number of recommendations which I have followed but my problem has not gone away. I am impressed with what I have seen with the experts on this site and finally am seeking expert help.
Note I am having to post this from another computer but have my laptop next to me.
Background: About 6 weeks ago I suddenly found that any attempt to reach a website via Firefox 3 failed. When I tried with IE7 a number of "linked to" urls were spawned and completely overtook IE such that only by turning off the computer completely was I able to stop this. I use Spybot and Adaware on occasion but now I downloaded a number of extra anti spy and anti malware programs and ran them, even purchased PC Spyware Doctor (normally I have just used Symantec AntiVirus). Various things were found, quarantined and/or removed. One possible factor, this happened around the time I made my last ZoneAlarm update. Don't have any direct correlation, but turning off ZoneAlarm does not make any difference.
When I forced open port 80 in Windows firewall I was able get to http sites in firefox but not MSIE7.
Current situation: after trying virtually every suggestion I found on this site and other similar ones, I can ping, reach sites via https, ftp, use VPN, Remote desktop, Email, etc. Just can't open a web page using a browser on port 80. A big problem is that I cannot update AV apps that use port 80 for their updates such as Malwarebytes.
Most recently I went into the Recovery Console and ran fixmbr. After this I was able in Safemode with networking to update all my anti spy and malware programs and ran complete scans and removed all problems that I was alerted to and then was able to visit an http site or two. Rebooted into XP and ran PC Spyware Doctor (which wanted to run only in full XP mode). But once again, found that I had no access to sites via port 80.