Hello Usnret26, try to boot the computer in [http://windows.microsoft.com/en-us/windows/start-computer-safe-mode#start-computer-safe-mode=windows-7 Windows Safe Mode with network support] (press F8 on the boot screen) and then see if that allows to uninstall firefox. Then go for a clean re-install, this means you remove Firefox program files and then reinstall Firefox. Delete the Firefox installation folder, which is located in one of these locations, by default on Windows: * C:\Program Files\Mozilla Firefox * C:\Program Files (x86)\Mozilla Firefox then # Download, with another browser, the latest Desktop version of Firefox from the next full installer : https://www.mozilla.org/firefox/all/ and save the setup file to your computer. # Double-click the downloaded installation file and go through the steps of the installation wizard. # Once the wizard is finished, choose to directly open Firefox after clicking the Finish button. Please report back to say if this helped you! Thank you.