This article describes why Firefox may start in Safe Mode when you expect it to start normally and how to fix the problem.
If you started Firefox in Safe Mode, it will remain in Safe Mode until Firefox is completely closed. The easiest way to make sure Firefox is completely closed is to restart your computer. Once your computer starts up again, start up Firefox.
When Firefox crashes at startup, the next time you launch Firefox it displays the Safe Mode window, which lets you choose between starting in Firefox Safe Mode or resetting Firefox refreshing Firefox because you may have something wrong with your configuration (such as graphics, add-ons, or third-party software). See Firefox crashes - Troubleshoot, prevent and get help fixing crashes for help solving crashes when starting Firefox.