Fly in the ointment
Let me throw this fly into the ointment for you. I have both a Windows Browser through Qwest and I also have Firefox as an auxillary browser, since for some sites I can't seem to use Windows to access and for some things, when I do access and try to use the links, the links show up as a "blank page." When that happens I go to Firefox gain access and can see the links without trouble. I have the updated current version of Firefox, which I think is 3.8.
All this talk of cookies got me to thinking. I have both a Regedit program, that cleans my registry as things are updated, but only on my command. I also have spysweeper which removes nasty items including cookies and Window Washer which will clean everything. I use Window Washer daily and my computer is set up through programing to dump all cookies and temporary internet files each time I turn off the computer after exiting the browser, which is once per day.
As a result I don't store cookies or temporary internet files. Both Firefox and Windows browsers have all my shortcuts. I have absolutely no problem getting onto TFL forums, specifically the M-14 Firing Line forum, from either browser.
I am going to suggest therefore that the problem lies with programing on a specific computer that is activated to prevent access to some programing, much as you might use to keep children from seeing adult sites and so forth. That's where I would start looking to see what constraints might exist on your computer. If you have a list of defaults under your security section start looking there. Another place is whether there is something that looks for current certificates and check that out as it will automatically exclude, sometimes without warning you, a site that it doesn't like the certificate of. Firefox is not as bad as microsoft about those things but they both have those kinds of things in the programing. I have found that many defaults aren't what we would all want. So whenever I set up a computer, one of the first things I do is to go through the default and security lists and set them up for me. The second thing is to drop the overall computer to "Medium" on security setting. "High" or "maximum" on a security setting will also exclude, automatically, anything the computer reads as suspect. That's one reason why I use two webroot programs, a McAfee Security program and a Max Registry Cleaner. Since doing that several years ago I have had no real problems with my PC at all. And I have the ultimate control, not Bill Gates or the people at microsoft. I have also turned off "automatic updates" so that I don't get some of the updates that are prone to problems. Microsoft does updates every so often that initially have problems that you can't fix and they weren't aware of when they installed them.
