Now, I've gotten this script error on an article at MLive.com, which is a website Firefox seems to have an incredibly difficult time loading promptly:

Script: chrome://browser/content/tabbrowser.xml:2412

My browser literally hung for 30 minutes before I was even offered the ability to terminate the script. What is going on, here?

Boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that has any effect.

You might need at least 3 GB (gigabytes) of RAM (Random Access Memory) to get rid of script errors.

I had the same problem with my computer for many, many months, slowing down my computer to a halt. However, once I upgraded to 3GB of RAM the problem COMPLETELY disappeared. I had only 1GB of RAM in my computer prior to that.

I had tried all of the other suggested fixes as well such as resetting Firefox, uninstalling Webroot Anti virus, turning off add ons, etc. Nothing worked. However, upgrading my RAM did work.

Right now, while I am writing this, I have over 80 tabs open in Firefox (yeah...I'm interesting in a lot of topics). However there is not a single script error or Flash problem taking place. Before the RAM upgrade however, I might only have four tabs open and my computer would freeze up with script errors.

I also noticed that computers that had at least 3GB of RAM did not have the script error problem even if they were running Webroot Anti-virus.

Please let me know if this apples to you (i.e., you have less than 3 GB of RAM) and if it does and you upgrade, let me know if the upgrade works. I bought my RAM at www.crucial.com They were very good on delivery and service. The website will even scan your computer and tell you what type of RAM you need and instructions on how to install it.

How much RAM do you have?

I have about 7.6GB.

Hi FireFoxFan1, I got a period of Not Responding on the MLive site with the message that Firefox was loading something from admin.brightcove.com. I didn't check the actual time — I left the computer for a few minutes, and it was okay when I returned. Note that I run NoScript so any additional time required to load ads and tracking scripts would not have been counted.

When you say Flash (Shockwave Flash) is only active on Youtube, have you set it to "Ask to Activate" (click-to-play) to ensure that it does not run on other sites until you approve them? If you haven't tried that, it could be useful as a diagnostic to see whether Flash is involved.

Open the Add-ons page. Either:

• Ctrl+Shift+a
• orange Firefox button (or Tools menu) > Add-ons

In the left column, click Plugins. Then find "Shockwave Flash" and change the drop-down control to Ask to Activate. On sites that want to use Flash, you will see some combination of the following:

• Notification icon (looks like a piece of Lego) in the address bar
• Notification in a black rectangle where the video player is on the page
• Infobar sliding down between the toolbar area and the page if the Flash is not visible in the main page (used behind the scenes or in a frame)

Does that make any difference?

No, I mean that I literally don't activate it until I'm ready to watch Youtube movies. It's set to "Never Activate" until I choose to turn it "Always Activate." I'm very aware of how to operate simple plugins.

I'm getting this script error that cripples my system for minutes on end, now:

Script: chrome://global/content/bindings/radio.xml:243

This particularly happened after I reinstalled all of the Microsoft .NET Framework programs with the Windows automatic update website. I reinstalled as I'd uninstalled them and it wrecked a few of my other programs.

Is there a .NET Framework version that I don't need? These things take up so much space, and I have no idea what they actually do beyond that. It took up 2GBs of my system that I really don't care to spare.

Hi FireFoxFan1, does the .Net framework appear as a plugin or extension on your Firefox add-ons page? If so, you could try disabling it there. If not, it might not be relevant.

While many sites use Microsoft's .Net technology, often recognizable by pages ending with .aspx, most high traffic websites do not. If this error is occurring on many popular sites, it may be unrelated, despite the timing.

Do you have the same profile and settings as you did when originally posting this question? Back then your More System Details showed that Firefox was set to wait forever if a script in a page was looping continuously, which avoids some annoying premature popup dialogs but can lock up Firefox for extended periods.

Try resetting the dom.max_script_run_time back to default (10 seconds) or to a number closer to the default (such as 30 seconds).

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box that appears above the list, type or paste script and pause while the list is filtered

(3) Assuming it is still bold and user set to 0 ("forever"), right-click the dom.max_script_run_time preference and choose Reset to return the value to 10 or double-click it and enter the desired value (in seconds).

I changed the runtim to what you told me to.

Unfortunately, this unresponsiv script has popped up:

Script: chrome://browser/content/tabbrowser.xml:3459

Hi FireFoxFan1, that change was basically to get to the dialog faster so Firefox wasn't frozen as long. I didn't mean that it would solve the original problem.

• Since you have done a clean install (removing C:\Programs\Mozilla Firefox\), that should rule out files dropped into the program folder hierarchy, at least until external software detects that its files are missing (most commonly at the next restart of Windows)

• Since you have done a Reset, or replicated the problem in a new profile, that should rule out settings problem except for system-installed plugins (still just Flash?) and extensions (none mentioned), at least until you start customizing

• Since you have disabled hardware acceleration, that should minimize the effect of any performance problems caused by graphics card driver incompatibilities

What does that leave? If the problem is with complex pages, presumably that means pages which pull in resources from a wide range of sources (multiple servers) and which use plenty of JavaScript. Could any of these be a factor?

• Security software which filters/cleans web retrievals?

• Security, privacy, or parental control software, or host file entries, which block or redirect requests to some sites?

• Security or privacy software that alters browser requests by removing or replacing some headers (e.g., referring site header)?

• Proxy, private VPN, or TOR service that alters the way Firefox's requests appear to websites?

• Malware? You can do supplemental scans using the tools listed in this article: Troubleshoot Firefox issues caused by malware.