Computer crashes and has to be shut down whenever Firefox is opened.

Question

The problem started when I tried to open specific websites and then it worsened so that whenever I attempt to go to a page other than the Firefox home page, my computer has to be shut down. I can open Firefox but I can't do anything else; it even bombs my computer when I try to do troubleshooting. The problem doesn't occur when I use either Safari or Chrome.
Have tried the following:
1. Resetting preferences.
2. Doing a clean reinstall.
3. Opening Firefox in safe mode.
4. Updating active plug-ins.
I can't send any crash reports because there are none listed. I think it's because the computer bombs and is unable to record any info. I've tried to attach the troubleshooter.xpi file below, but it never loads. Don't know if it's because I'm working in Safari.
Application Basics
Name: Firefox
Version: 35.0
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:35.0) Gecko/20100101 Firefox/35.0
Multiprocess Windows: 0/1
Crash Reports for the Last 3 Days
All Crash Reports
Extensions
Name: DivX Plus Web Player HTML5 <video>
Version: 2.1.2.145
Enabled: false
ID: {23fcfd51-4958-4f00-80a3-ae97e717ed8b}
Graphics
Device ID: 0x71c5
GPU Accelerated Windows: 0/1 Basic Blocked for your graphics card because of unresolved driver issues.
Vendor ID: 0x1002
WebGL Renderer: ATI Technologies Inc. -- ATI Radeon X1600 OpenGL Engine
windowLayerManagerRemote: false
AzureCanvasBackend: quartz
AzureContentBackend: quartz
AzureFallbackCanvasBackend: none
AzureSkiaAccelerated: 0
Important Modified Preferences
browser.cache.disk.capacity: 358400
browser.cache.disk.smart_size.first_run: false
browser.cache.disk.smart_size.use_old_max: false
browser.cache.frecency_experiment: 2
browser.places.smartBookmarksVersion: 7
browser.startup.homepage_override.buildID: 20150108202552
browser.startup.homepage_override.mstone: 35.0
extensions.lastAppVersion: 35.0
gfx.blacklist.direct2d: 3
gfx.blacklist.layers.direct3d9: 3
gfx.blacklist.webgl.msaa: 4
media.gmp-gmpopenh264.lastUpdate: 1421453305
media.gmp-gmpopenh264.version: 1.1
media.gmp-manager.lastCheck: 1421453305
network.cookie.prefsMigrated: true
places.history.expiration.transient_current_max_pages: 80531
plugin.disable_full_page_plugin_for_types: application/pdf
privacy.sanitize.migrateFx3Prefs: true
Important Locked Preferences
JavaScript
Incremental GC: true
Accessibility
Activated: false
Prevent Accessibility: 0
Library Versions
NSPR
Expected minimum version: 4.10.7
Version in use: 4.10.7
NSS
Expected minimum version: 3.17.2 Basic ECC
Version in use: 3.17.2 Basic ECC
NSSSMIME
Expected minimum version: 3.17.2 Basic ECC
Version in use: 3.17.2 Basic ECC
NSSSSL
Expected minimum version: 3.17.2 Basic ECC
Version in use: 3.17.2 Basic ECC
NSSUTIL
Expected minimum version: 3.17.2
Version in use: 3.17.2
Experimental Features
Please note that I can't update my computer's OS X because it's too old for the latest versions.
Please help me fix this problem. Firefox has been my favorite browser for years and I'd hate to have to use something else after all this time. Thank you.

Answer 1

Ok, sorry to hear that the crashes are not recording. I did notice that there was an issue with the graphics card. There are two things we can try:
Try disabling graphics hardware acceleration. Since this feature was added to Firefox, it has gradually improved, but there still are a few glitches.
You might need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.).
Then perform these steps:
#Open Firefox ''Options'' window (''Preferences'' on Mac or Linux) as follows:
#* In Firefox 29.0 and above, click the menu button [[Image:New Fx Menu]] and select ''Options'' for Windows or ''Preferences'' on Mac or Linux.
#* In Firefox 28.0 and previous versions, click the orange Firefox button at the top left, then select the "Options" button, or, if there is no Firefox button at the top, go to Tools > Options.
#In the Firefox Options (or Preferences) window, click the ''Advanced'' tab, then select ''General''.
#In the settings list, you should find the ''Use hardware acceleration when available'' checkbox. Uncheck this checkbox.
#Now, restart Firefox and see if the problems persist.
Additionally, please check for updates for your graphics driver by following the steps mentioned in the following Knowledge base articles:
* [[Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems]]
Or try this:
* [[Upgrade your graphics drivers to use hardware acceleration and WebGL]]
Did this fix your problems? Please report back to us!
Thank you.