If you need Adobe Flash Player installed on your system, simply go here: Get Adobe Flash Player . Please be sure to UNCHECK the McAfee as that is just additional BLOAT in my opinion.
Here are few more articles concerning disable protected mode in Flash player ( Adobe site article )
All you have to do is click the link below, and the script will open up in readable form in case you want to see what it does and how it does it. When you are ready just up at the top click download, and then run it. NOTE: You might have to right click and run as admin if you get any permission or access denied, i cannot resolve these issues
Disable Protect Mode script
If this issue does not resolve your Mozilla Firefox crashing Flash Player then you can check out my other Blog for additional fixes. HERE
YouTube video tutorial
Please note that i can provide limited technical support for these. This particular script is self-explanatory.
NEVER INSTALL FLASH PLAYER MANUALLY AGAINBe sure to Check out my other post for complete uninstall, clean up of all flash files, and re-install from a script. http://adobeflashcleanup.blogspot.com/