Port 80 dies randomly, everything else works

Well... I had a Win 7 Ultimate 64bit on this very machine (the one in my preferences) for almost 3 years until the moment when I said to myself: OK, time to refresh. And that only because my port 80 would die sometimes....sometimes thrice an hour for 10-15 min, sometimes twice a day. But it would happen every day. I re-installed with the hope it was just a bad Win installation but it happened again after just an hour in. What I tried? Well, I certainly tried a new router, but it didn't help. I knew it wouldn't since I also run Linux and OS X in home network and none is affected by this. I scanned old and new Win 7 with every possible malware finder, antivirus..etc. Even bought one (I have an "allergy" when it comes to A/Vs and such in general).. I went drastic today, I disconnected all devices (hdds, usbs, dvdroms, pcie) just to prove my point.. left a single 60 GB SSD with brand new win 7 with default drivers .. Took several hours but I still lost port 80 (it seems to be just port 80 since only browsers and windows LIVE are affected on my system)...Skype, FTP, rsync.. they'll all work just fine while nothing else web-wise does.

Help please! Any suggestions will be tested and reported.

I mean, no browser will load any page (since all web sites work on default port 80, unless specified otherwise ), Windows Live Mail [desktop] will also not connect (also port 80, trying to connect to .com mail server), but skype, utorrent, or a webpage that is not on port 80 will work fine. Ping WILL work since it goes through ICMP and ports are not used. It's not modem issue because the rest of the computers (Debian and OS X) can open pages fine while the one with Win 7 can't. It's a fresh Windows installation. I'll still try pinging anything when this happens and I'm home. Now have to go to work.
TIA.

Kaktussoft said:

I can't believe it's just a port 80 problem. Please do

Code:

nslookup  google.com

To prove it's not a DNS problem

OK, just got in. Will do that if it drops again while I'm here.

Sorry.. I was off town (travelling a lot actually) ...

@logicearth Well I don't use any security software. I get a brain disease when I install one.

@Kaktussoft .... Well it's interesting... The moment browsers die, I get various timeouts (nslookup) for the first 10-20 seconds while it's happening and then it shows everything fine, but the browsers are down for another several minutes.. sometimes more than 10 (or it just happens a few times in a row and I can't put a start and end point of it). It's really annoying - I'm moderating my websites from the Win computer (abroad most of the time) and when it's down it really freaks me out.. My iMac is just lame. Thank Unix for Linux so I can sustain my site's life on a second partition... So.. any advice ?

Britton30: No, no proxy here. I'll meddle with Google's DNS service when I get more free time. Actually up until few days ago I had no DNS specified in Windows, then I put the default ones that my provider advertises on their website and the problem is less obvious but still present.
As to why I am against antivirus software (the brain disease thing was just a metaphor obviously ) is because they are more trouble than they they're worth. Such software is most useful for people who just use computers to download stuff from suspicious places and waste time in facebook, accepting all sorts of friendship requests :)