Firefox has hardware acceleration set to "on" by default, but it's still young, which means some video cards or drivers might have problems with it. You can try to disable hardware acceleration to see if that alleviates your problems.

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 for Firefox version 29.0 and above:

• Click the menu button and select Options for Windows or Preferences on Mac or Linux. For 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 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

• Upgrade your graphics drivers to use hardware acceleration and WebGL

Try setting javascript.options.baselinejit to false in about:config:

• Navigate to about:config in your Address Bar
• Press the "I'll be careful, I promise!" button to proceed
• Search for javascript.options.baselinejit and set it to false by right clicking the pref and selecting Toggle.
• Restart Firefox and see if it works properly.

Your System Details shows;

Installed Plug-ins

Adobe PDF Plug-In For Firefox and Netscape 10.1.10 Adobe PDF Plug-In For Firefox and Netscape "9.5.5"

Having more than one version of a program may cause issues.

There are other things that need your attention.

Your System Details list shows that you have a user.js file in the profile folder to initialize prefs each time Firefox starts.

The user.js file is only present if you or other software has created this file and normally it wouldn't be there. You can check its content with a plain text editor (right-click: Open with) if you didn't create this file yourself.

The user.js file is read each time Firefox is started and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

See:

• http://kb.mozillazine.org/Preferences_not_saved