By soft clicking noise, what exactly do you mean? If you are hearing a clicking noise in your computer that then stopped, it is possibly your hard drive dying, or a fan in the computer that dies. You shouldn't have "clicking" noises in a PC.

As for system Idle Process, that is just the percentage of the CPU that isn't being used, if that is at 99%, it means that only 1% of your CPU is being used at that moment.

Now, as for starting Firefox in Safe Mode, let's try this. Restart your computer, then while you start Firefox, hold down the Shift Key. You should have a small box open up with a bunch of checkboxes. Don't check any of them right now. Just Continue in Safe Mode. This is Firefox safe mode, all customizations, themes, addons, etc. will be disabled. If you don't get the freezing here, restart Firefox, and disable your add-ons one by one until you find the culprit.

Also, you can try updating your graphics driver to see if this is an issue with Hardware acceleration. https://support.mozilla.org/en-US/kb/how-do-i-upgrade-my-graphics-drivers has more details.

Thanks for trying, but I lost faith in your answer by the end of the 1st paragraph. That soft clicking noise has been present on every single computer I've ever used in the past 15 years without fail. New or old, healthy or weak, expensive or cheap, desktop or laptop, school, work, or home... It's the sound of the hard drive being accessed, & it's completely normal. My problem is that that sound has STOPPED. but the harddrive is still accessible. It sounds like it got stuck in the middle of something. And when that silence appeared, so did the problems.

Add'l info: I also noticed that when I open task manager there's some kind of DLL running that disappears. In the description I can see the word dcom for just a split second but then it disappears before I can click on it. I suspect malware. Maybe this screencap will help?

Did you try Starting Firefox in Safe Mode and updating your graphics Driver? No matter what noise your hard drive is making or not making, if it isn't dying, that shouldn't be having any impact on Firefox's normal operation. Problems with computer hardware are beyond the scope of this forum unfortunately, so I'd recommend if you are having hard drive problems to go to a local PC repair shop (ie. not geek Squad) and have them check it out for you. If you aren't having problems with it, then you are set to go.

would anybody with a >20% success rate like to try this?

I never said the lack of the HD sound CAUSED the problem.....the silence just started at the same time the other problems (FF freezing) started. A good diagnostician will take that as a sign that they are likely related.

This is definitely a software-related problem. If I'm not mistaken, it started after updating Firefox & some other software. I noticed the AVG gadget I use isn't available for this FF update....is there any chance my HD is trying to activate that & failing? Any help is appreciated.

After the warm reception that Tylerdowner got I think a few people may be hesitant in offering assistance here.

With Firefox not running at all, go to Start, All Programs, Mozilla Firefox, Mozilla Firefox (safe mode).

As for not being able to kill it normally, I have no idea. It might be worth defragmenting the disk, (Control Panel, System and Security, defragment your hard drive [under the administrative tools heading]), but I doubt it will help all that much.

My guess is that your hard drive is close to death, and it would be best to replace it now, before it gets worse and you lose all of your data. I second Tylerdowner's suggestion of taking it to a local repair shop to at least get it looked at.

On the plus side, your CPU is fine, so no need to worry about that.