Perform the suggestions mentioned in the following articles:

• Clear Cookies & Cache
• Flash Plugin - Keep it up to date and troubleshoot problems

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The problem is NOT with a Flash Player plug-in . I have not been able to download the Flash Player at all !

more information from a duplicate thread - moderator

The final window of the installation process states "installaqtion failed-cannot find action list" I don't even know what a "action list" is !

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems
• Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

Check and tell if its working.