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I keep getting a message that says "Firefox.exe – application error The exception unknown software exception (0xc0000417) occurred in the application at location 0x78579231" and when i click ok it closes my firefox window.

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  • Last reply by Xircal

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I've already tried uninstalling firefox and then reinstalling it. (i've done this twice but it still keeps giving me this message.

I've already tried uninstalling firefox and then reinstalling it. (i've done this twice but it still keeps giving me this message.

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Please reinstall Firefox as follows:

  1. Go to Download Firefox 4.0.1 and download a fresh installation file to the desktop using IE8.

  2. Then go to Add/Remove Programs, scroll down to "Mozilla Firefox" and remove it, choosing to keep your bookmarks, customizations etc., (don't checkmark the box).

  3. Next, reboot and delete the folder called "Mozilla Firefox" at this location: C:\Program Files\Mozilla Firefox

  4. Finally run the installation file you downloaded to the desktop earlier.

Your bookmarks, customizations etc., are maintained in a different location and will become available to you again once you complete the installation.