First, let's make sure there is no monkey business.

You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Then do this;

Let’s do a full clean re-install; Download Firefox For All languages And Systems {web link} Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Mac: Open the "Applications" folder.
https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac Linux: Check your user manual.

Do Not remove the profiles folder.

Look for, and rename any Mozilla or Firefox program folders by adding .old to them. Do not rename the Mozilla Thunderbird folder.

After rebooting the computer, run a registry scanner. Then run the installer. If all goes well, remove the OLD folders when you are done.

If there is a problem, start your Computer in safe mode and try again.

Starting The Computer In Safe Mode;
Free Online Encyclopedia

The problem has not gone away, and I don't believe there's any malware. The malware are SCRIPTS, and Firefox's handling of them, or script blocking plugins.

Websites today are SHOT THRU with scripts.

Renaming the Profile to .OLD did nothing, it was simply regenerated and I'd like to DELETE the profile completely.. it's 16MB.

What I really want to do is UNINSTALL this version and go back to 43.0.1_64.

Why do we always have to `update´ to the latest? Because it's good for THEM? This is not being flippant.. it's a real concern.

Thanks,

-Ed

Hi, have a look at - Warning Unresponsive script - What it means and how to fix it

And Firefox uses too much memory or CPU resources - How to fix

If you are sure you want to delete a profile - Profile Manager - Create, remove or switch Firefox profiles

There is no reason why using an old version will fix your problem, but if you really want to try it - Install an older version of Firefox

If your question is resolved by this or another answer, please take a minute to let us know. Thank you!

Hi and thanks for the reply. Yes, I'd like to start a NEW profile however retain the bookmarks. The policy here is `flush often´ when it comes to browsers.

It's not just a matter of "unresponsive scripts", the browser and entire OS in LOCKED OUT (no mouse, no kybd) while the hard drive is being thrashed. It feels like I'm getting raped.. like someone is rifling through my files!

This online behavior is totally unacceptable. And that's why I'm referring to v43, because it worked very well with no issues. In fact, I'm thinking of reinstalling the entire OS.

Thanks,

-Ed

Ed said

Renaming the Profile to .OLD did nothing, it was simply regenerated

Firefox will create any missing files using default data.

Ed said

And that's why I'm referring to v43

Look for the directory of the version that you want. Install an older version of Firefox {web link} But remember that old versions may have security issues.

Thanks guys for the helpful replies,

Here's the full story. When v43 was current, I was checking for updates by doing Help, About, Check for Updates - and saw when v44 (or whatever) came out, and did indeed update.

Right way this behavior started, so within an hour I did a System Restore back to v43.

Months went by, and then an online bank started nagging to update Firefox.. with an IN YOUR FACE banner splash. That was a RED flag! Security for who? them?

So I held off, and held off, and finally went for it. Big mistake apparently.

I'd like to start a blog someday, but all those websites are riddled with a dozen or more third party hosts/scripts not to mention Google.. block, block, block... thrash, lockup, thrash, etc. Where does it end?

Now today I see v49.0.2 available. What's the point? Suppose Flash player will also want an update?  :)

-Ed

All or most programs go thru updating. Mostly to fix errors or make the program better. This includes Firefox and Flash.