I just tried uninstalling firefox and reinstalling it; that didn't work, still have problems. So I uninstalled or disabled all but the basic add ons/plug ins that I need, but still the problem exists! In fact when I open the add ons that freezes and I have to use control/alt/delete to kill the thing so I can restart firefox. Please help!!!!!!!!!

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).
See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all your extensions and then try to find which is causing it by enabling one at a time until the problem reappears.
You can use "Disable all add-ons" on the Safe mode start window to disable all extensions.
You have to close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

Create a new profile as a test to check if your current profile is causing the problems.

See Basic Troubleshooting: Make a new profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins"

If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)

See http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

I downloaded 3.5.15. It worked great. One day, Firefox auto-upgraded to 3.5.16. It hangs like crazy on a regular basis and I have to open the task manager, end the process, and put the process in realtime just to start over. I turned off auto updates, went back to the official download pages, and lo and behold, only 3.5.16 is available. I want to know how to undo the update and get 3.5.15 back. Please don't tell me to check my plugins and add-ons, Firefox worked fine before the "upgrade". Please don't tell me to upgrade to 3.6, it's absolutely abysmal. I just want 3.5.15 back, that's all I'm asking for.

EDIT: Oh thank God, nevermind, I found out I still had the installer saved in my downloads folder. I still think 3.5.15 should be available, though.

I saved my installer too - but now what do I do?

Go to ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/ , click on Mozilla Firefox under Internet, and you can download ANY version of Firefox that was ever created.

edit: replaced random download site link

I was so pissed when Mozilla slipped a warning about my Add-ons not being compatible until I upgraded. It said nothing about "upgrade now" in the message; just and OK button.

I go to school online, and the university is in the process of upgrading their system to be compatible to the new Firefox version. In the meantime, these azzclowns have me wasting time with their version 12, and having to restore the version which allows me to presently attend class.

No thanks at all to the genius-bar in this little shop of horrors.