Does that happen if you start in troubleshoot mode (or use a new profile)? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems (also deals with hardware acceleration) https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles#w_start-the-profile-manager-when-firefox-is-closed