We're sorry to hear that Firefox is crashing when you open it. Please do the following to give us crash IDs that will help us understand more about the crash.

1. (OS X 10.6 or previous) Click the Finder icon in the dock. Your home folder will be selected. In the right side of the window, click the Library folder to open it. Then open the "Application Support" folder, the "Firefox" folder, the "Crash Reports" folder and finally the "submitted" folder.
   (OS X 10.7 or above) Click the Finder icon in the dock. On the menu bar, click the Go menu, hold down the option or alt key and select Library. A window will open containing your Library folder. Then open the "Application Support" folder, the "Firefox" folder, the "Crash Reports" folder and finally the "submitted" folder.
2. Open the 5 most recent files with a text editor and copy the IDs.
3. Paste each ID with bp- into the reply window on the forums.

Thanks in advance!

You can find more information and troubleshooting steps in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

Firefox just had two security updates (36.0.3 and 36.0.4) in the past few days. Did the problem start after one of those?

Could you test in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any difference in scrolling performance?