Looks like there was a slight increase in the number of crashes with this signature, however there is still not alot known about it.

Would it be possible to see if this happens with nothing but Firefox open?

Since it is a start up crash 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.

So the question that we are asking for the bug info is:

1. any startup plugins, pages, addons?
2. What else was he running at the time of launching firefox?
3. Plain Text... was mentioned in the crash report: what font are you using?

I just tried with all applications off.

Because I have deleted the Firefox folder in an attempt to do a clean install I only have 4 ids right now.

Also to my knowledge I have no add-ons. I deleted the application support folder for my current user (I understand this is where add-ons go), checked that there are no global add-ons, and downloaded Adobe's tool for uninstalling flash. And the last time I reinstalled I deleted the firefox plist.

I don't know what font I'm using because I can't start the program... not sure why that would be relevant anyway.

Crash ID: bp-cfc0cedf-f480-4ea9-a164-608042150127 Crash ID: bp-554928df-de36-4d6c-8965-d4bd02150127 Crash ID: bp-87b42942-f3dd-4280-b9ff-a44ba2150129

Just now with no applications running: Crash ID: bp-26928442-1d9a-4900-b1c9-f36442150129

So just to confirm: exactly the same behaviour with no applications running.

Thank you for the confirmation. The experts are seeing the WebP image codec as a possible cause, however I am not entirely sure what this is. If you disable this does the crash continue?

This module: libwep_hook.dylib

Any idea what this might be?

If you delete Application Support, you are deleting all the profiles for all Mozilla applications except Thunderbird. The add-ons go into a subdirectory in the profile for the particular application, and its name is "extensions".

The crash report flagged these programs;

libwep_ff.dylib = unknown

libsystem_kernel.dylib =  ? Word for Mac complete removal of Office 2008

libsystem_pthread.dylib =  ? Word for Mac

libsystem_malloc.dylib = unknown Mac ?

libdispatch.dylib =  ? Word for Mac

Download the full installers for any Microsoft programs you have. Save them someplace safe. Now Uninstall All Microsoft on your system. Reboot. Run a registry checker / cleaner. Reboot. Now test the computer. Are you having any problems?

The only MS application I have is Remote Desktop. According to this support document you only need to delete the app. https://discussions.apple.com/thread/5856710

I think the suggestion that it is related to WEBP is due to the fact that if you search google for libwep (which is in the crash report) it searches instead for libwebp (not in the crash report) because the former is rare and the latter is common.

I actually think it's likely a bug in Firefox WEP library which *probably* exists (I am not a developer) https://developer.mozilla.org/en-US/docs/Web/API/WiFi_Information_API#WEP.2FWPA

Uninstalled remote desktop. Did not clean the registry since this is a Mac and doesn't have one. Restarted. Firefox still crashes. Crash ID: bp-13c21951-9493-477e-8c8b-a79f72150130

When I search the web, it is for the whole program name; libwep_ff.dylib

The last report is the same as the others, plus;

Signature nsACString_internal::Assign

A Huge ! number of users have the same issues, and always, the Microsoft programs on Macs were flagged. Is it caused by one of these or something fighting them . . . . . . . I urge you to remove those programs for now.

Sorry, when I search for libwep_ff.dylib I get literally no results. I tried on yahoo and bing for good measure.

Currently I have no MS software on my computer. I am using Open Office.

Let it go for a while. Any crashes, post them here after you get a few.