New answers tagged firefox
First try 'verify disk permissions' using Disk utility and verify/repair disk. Also, have you tried with Apple Hardware Test? The instructions for Hardware Test are detailed here: Using Apple Hardware Test
emma24xia's answer is for Windows and not applicable on a Mac. On a Mac you would do it this way. Open up Applications/Utilities and launch Activity Monitor. Look for Firefox in that list. Select it and click the stop-sign icon to force quit that process.
I find a solution online here, you can check it. https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding
Had problems with Flash as well. Also Firefox would not allow setting "Always activate". After trying to load the latest version (unsuccessfully) many times I uninstalled it from my system (Windows XP) and downloaded the latest version - not through Adobe - but at http://labs.adobe.com/downloads/flashplayer.html Load the latest 126.96.36.199 Beta version. No ...
Under Safari/Preferences/Security click the last box that states "Internet Plug-ins: Allow Plug-ins" So simple and it worked for me running Safari on 2008 MBP with OX X Yosemite
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