If you installed the 64-bit version of Firefox over an existing 32-bit installation, there might be some loose ends. You could check whether anything in this article helps: [[How to switch from 32-bit to 64-bit Firefox]] More generally, which of these program folders do you have: C:\Program Files (x86)\Mozilla Firefox - ''normal location of 32-bit Firefox on 64-bit Windows'' C:\Program Files\Mozilla Firefox - ''normal location of 64-bit Firefox on 64-bit Windows, and 32-bit Firefox on 32-bit Windows'' and if you check the Target of the shortcut, does it point to the correct location? Perhaps it's easiest to remove the shortcut and create a new one: in the relevant program folder, right-click the '''firefox.exe''' file, and use Send To > Desktop (create shortcut)