Did you upgrade Windows on a system that already had Firefox, or is this a new installation of Firefox? Could you try starting Firefox in its Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: [[Troubleshoot Firefox issues using Safe Mode]]. Hold down the Shift key when starting Firefox. In the small dialog that should appear, click "Start in Safe Mode" (''not'' Reset) Can you get up and running? ---- When Firefox crashes, it usually records information about what was happening at that moment. You can submit that data to Mozilla and share it with forum volunteers to see whether it points to the solution. Please check the support article "[[Firefox Crashes]]" (especially the last section) for steps to get those crash IDs, and then post some of the recent ones here.