Spindrift, For further investigation is this on the plugin check page? For reference:

• https://www.mozilla.org/en-US/plugincheck/

If so, please clear the cache and cookies to request a fresh page to detect changes. If the version in about:plugins is up to date Firefox has recognized it.

If Firefox does not recognize the update, remove the plugin from the about:extensions page and restart the browser. (A reinstall of Flash may also be necessary)

Thanks for your comeback... Although I can get the about:plugins page up, when I try about:extensions I get the 'The address isn't valid' page so I can't remove the plugin. Any thoughts? Spindrift

I noticed in the information included in the about:plugins page under Shockwave Flash, the Path: line was showing-

<Path: C:\WINDOWS\SysWOW64\Macromed\Flash\NPSWF32_16_0_0_287.dll,C:\WINDOWS\SysWOW64\Macromed\Flash\NPSWF32_16_0_0_305.dll>

The .dll file for outdated version 287 was still there and listed first before the current version 305. I deleted the version 287 .dll and on restarting Firefox and checking the plug-ins again the problem appears to have been solved. Regards - Spindrift