If not able to open Firefox then start Firefox in Safe Mode {https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode} by holding down the <Shift> key (Mac = Options key), and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh). -> Open Mozilla's Plugin Check {http://www.mozilla.org/plugincheck/} -> If you see a notice that you need to update Flash even after installing the latest Flash version, uninstall and reinstall Flash -> Exit Safe Mode (close Firefox) -> Open Firefox normally, check if issue is resolved. If issue not resolved then, check if the info provided in the link below applies to you (if so, you can open Firefox in Safe Mode and follow the instructions given therein): https://support.mozilla.org/en-US/kb/adobe-flash-protected-mode-firefox Hope this helps!

Each report shows a different version of Firefox. What's with this?