Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

Please report back to see if this helped you!

Yes, but I get the same error message when I try to uninstall it, and in safe mode when I try to uninstall it it doesn't do anything

Welp, I just went ahead and installed it without trying to uninstall it, and it now works, even though it was the same version I already had installed. Thank you

Yes XPCOM errors require a overinstall (on top of) or a reinstall.

hello there!! i just wanted to let you know that you rock ; ) i followed your suggestion about firefox cause i was having same problem right after updates and i installed it again,it told me to upgrade,and thats all i had to do,thank you so so much ,good luck everyone