Did the error message say more? You could send us a screenshotof this message, maybe we will get useful information. (instruction here: [[How do I create a screenshot of my problem?]])

You can try this: *Download the Firefox installer and save the file to the desktop<br>https://www.mozilla.org/en-US/firefox/all/ *Start the installation with a double-click on the desktop icon *https://support.mozilla.org/kb/Installing+Firefox+on+Windows ---- If there are still problems then make sure that you have write permission for the Firefox program folder. Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) to see if that helps. *http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/