If the Flash plugin continues to crash, updating to the latest version of Flash may fix the issue.

https://support.mozilla.org/en-US/kb/adobe-flash-plugin-has-crashed

it will help definitely :-)

When Firefox crashes, it usually records information about what was happening at that moment. You often will see the Mozilla Crash Reporter dialog come up. You can submit that data to Mozilla and share it with forum volunteers to see whether it points to the solution. Please check the last section of the support article "Firefox Crashes" for steps to get those crash IDs, and then post some of the recent ones here.

If that's not possible, could you test in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any less crashy?