Have you tried this (source: ): If the normal uninstallation process (as mentioned above) fails, then please try Microsoft Windows Installer Cleanup Utility. This tool will ensure that all irrelevant Java Runtime Environment Microsoft Installer (msi) registries are removed. Detailed information and download is available at: Removal instructions:. Download the Microsoft Installer Clean Up utility file and save it on your desktop. Double click on executable file.

1. Completely Uninstall Firefox

The installation process will start. Follow the instructions accordingly. Once installation process is over, go to Start - All Programs - Run Windows Install Clean Up utility. This will launch the Windows Installer Clean Up utility dialog box. Under the Installed products list, select the desired JRE version that you want to remove.

Completely Uninstall Firefox

Click Remove and Exit.