Could you try disabling some features disabled in Firefox's Safe Mode. This often is more practical than spending an entire day browsing in Safe Mode, although you could try that if you prefer (see: Diagnose Firefox issues using Troubleshoot Mode).

Disable hardware acceleration of graphics

This works around the occasional incompatibility with graphics drivers.

orange Firefox button (or Tools menu) > Options > Advanced

On the "General" mini-tab, uncheck the box for "Use hardware acceleration when available"

Disable the new Firefox 23 Baseline JavaScript compiler and the IonMonkey JavaScript compiler introduced in Firefox 18

It might not be necessary to disable both, but as I am not sure how they interrelate, it seems safest to treat them as a pair.

(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 above the list, type or paste java and pause while the list is filtered

(3) Double-click each of the following preferences to switch their value to false:

(A) javascript.options.baselinejit.content

(B) javascript.options.baselinejit.chrome

(C) javascript.options.ion.content

Exit and restart Firefox to have the changes take effect.

Is Firefox (more) stable?

• http://kb.mozillazine.org/Firefox_crashes
• https://support.mozilla.org/en-US/kb/Firefox%20crashes

Honestly, it's hard to say right now since I just tried out your instructions and rebooted it. Over the last few days it has occasionally gone several hours before crashing (although some of the time it also fails within 15 minutes). Even if it doesn't crash over the next couple of hours it could be just on one of its "good" times.

I'm not a programmer, so please forgive me for asking this question--why would Javascript compilers introduced in Firefox 18 and 23 suddenly start crashing the browser in Firefox 24 when it hasn't before?

Either way, thanks for the tip. I'm trying it out; hopefully it will work.

Even though the compilers were added before, they are constantly tweaked. Sometimes fixing a bug will unexpectedly cause a new one.

Thanks for the help so far, but I (unfortunately) have an update: 40 minutes and it crashed. Other ideas I could try next? (FYI: I looked at the help file finitarry posted, and I've tried most of them except for safe mode, and I'm not sure how safe mode is supposed to help me figure out which one it is)

You can use one of these to start Firefox in Safe Mode:

• On Windows, hold down the Shift key while starting Firefox with a double-click on the Firefox desktop shortcut
• On Mac, hold down the Options key while starting Firefox
• Help > Restart with Add-ons Disabled

• https://support.mozilla.org/kb/Safe+Mode

In Firefox Safe mode these changes are effective:

• all extensions are disabled
• default theme is used (no persona)
• userChrome.css and userContent.css are ignored
• default toolbar layout is used (localstore-safe.rdf)
• Javascript JIT compilera are disabled (javascript.options.*jit)
• hardware acceleration is disabled

• plugins are not affected
• preferences are not affected

You have Norton software, probably on both computers. That is sometimes causing Firefox 24 crashes

• https://community.norton.com/t5/Norton-Toolbar-Norton-Identity/Firefox-24-still-crashes-when-the-NIS-toolbar-is-enabled/td-p/1023987
• Note the Norton Forum site has Mixed Content issues detected by Google Chrome and Firefox. You may need to click the shield and disable protection to view the site navigation. A problem I trust the site is aware of.

Does disabling or uninstalling some of the Norton extras solve the problem ?

Normally Norton synchronise the releases of working binaries with the Release of Firefox. Something seems to have gone wrong this time.

Thanks for the tip. I disabled Norton Toolbar. Let's see how this turns out? Based on the link you posted, it seems like there's a pretty good chance that's the culprit. I'll check in with an answer when I think it looks good or when it starts crashing again.

It was almost certainly Norton Identity Safe (NIS) Toolbar; I've been using both computers for a few days with no crashes since I disabled it. Thanks to everyone who answered. I appreciate it.

Thanks for posting back Jonathan. Glad we were able to help.

There may be different Norton software and patches involved in some of these crash situations. I have certainly noted a variety of related crash signatures.

Thanks for posting back to say disabling the toolbar resolved your issue, at least as a temporary work around.

I suggest anyone with Norton related crashes watches

• these Firefox threads /questions/971603 & /questions/971689
• the Norton forum thread https://community.norton.com/t5/Norton-Toolbar-Norton-Identity/Firefox-24-still-crashes-when-the-NIS-toolbar-is-enabled/m-p/1027739#M14000