Microsoft ended support for Silverlight. I guess you have version 5 as that was the last one. Firefox ended support with ver 57+ as used old NPAPI plug-in's https://support.microsoft.com/en-ca/lifecycle/search?alpha=Silverlight%205 and https://www.theinquirer.net/inquirer/news/2416200/microsoft-were-not-killing-silverlight-in-windows-10-but-stop-using-it-anyway and https://www.theregister.co.uk/2015/07/02/microsoft_silverlight/ and https://social.msdn.microsoft.com/Forums/en-US/17ef0df7-1980-47db-b5dc-303b2a5f28fc/what-does-it-mean-end-of-life-of-silverlight-any-alternatives-from-microsoft?forum=silverlightgen

So HTML5 is the replacement and all modern browsers support that. Though old Video Card Drivers can restrict it.

Windows 10 has replaced your old Video Card Drivers with their own : adapterDescription: Intel(R) Q35 Express Chipset Family (Microsoft Corporation - WDDM 1.0) driverDate: 10-1-2012 and their are issues : failures: [u'CP+[GFX1]: Potential driver version mismatch ignored due to missing DLLs igd10umd32 v= and igd10iumd32 v=', u'CP+[GFX1]: Potential driver version mismatch ignored due to missing DLLs igd10umd32 v= and igd10iumd32 v=', u'CP+[GFX1]: Potential driver version mismatch ignored due to missing DLLs igd10umd32 v= and igd10iumd32 v=', u'CP+[GFX1]: Potential driver version mismatch ignored due to missing DLLs igd10umd32 v= and igd10iumd32 v=', u'CP+[GFX1]: Potential driver version mismatch ignored due to missing DLLs igd10umd32 v= and igd10iumd32 v=']

Solution new card or new system. May want to uninstall the video card in Devices (yes it is still there in WIn10) Use search for Devices or Control Panel. After deleting it and restarting it will reinstall the drivers. Which may or may not fix things.

for some : Repair System Registry and Files

(FOR DOING Above & Below - WINDOWS All OTHER VERSIONS - Use Search To Find Command Prompt ** Enter CMD.exe to Find COMMAND PROMPT Then Right Click & RUN AS ADMIN)

To run the SFC command use the Windows key + X keyboard shortcut to open the Power User menu and select Command Prompt (Admin). Type "SFC /SCANNOW" (without quotes or copy/paste) and press Enter. For more information on using SFC, please refer to the Microsoft KB: Use the System File Checker tool to repair missing or corrupted system files

Run the Windows Deployment Image Servicing and Management (DISM) and System File Checker (SFC) tools as Administrator. The DISM and SFC tools scan the integrity of the Windows image and all protected system files replaces corrupted, damaged and incorrect versions. (FOR DOING Above & Below - WINDOWS All OTHER VERSIONS - Use Search To Find Command Prompt ** Enter CMD.exe to Find COMMAND PROMPT Then Right Click & RUN AS ADMIN) Type "DISM /Online /Cleanup-Image /RestoreHealth" (without quotes or copy/paste) and press Enter.

Windows 10 To run the DISM command use the Windows key + X keyboard shortcut to open the Power User menu, then select Command Prompt (Admin). Type "DISM /Online /Cleanup-Image /RestoreHealth" (without quotes or copy/paste) and press Enter. Reboot After.

Note : SFC fixes files locally using files found on your system. Note : DISM goes up to Microsoft for new ones.

Please let us know if this solved your issue or if need further assistance.

You need to use the Firefox 52.5.2 ESR version if you want to use the Silverlight plugin.

Firefox 52.5.2 ESR:

• https://www.mozilla.org/en-US/firefox/organizations/all/
• https://www.mozilla.org/en-US/firefox/52.5.2/releasenotes/

Why-do-Java-Silverlight-Adobe-Acrobat-and-other-plugins-no longer work.

• https://support.mozilla.org/en-US/kb/npapi-plugins

When installing the older version 52.5.2 ESR all is good except to install it only offers the "upgrade" tab to install...

What do you mean with "it only offers the "upgrade" tab to install" ?

You can uninstall the current 57.0.2 release and install the 52.5.2 ESR version. You can't switch the update channel otherwise.

Note the 52.5.2 is not really old:

• Version 52.5.2, first offered to ESR channel users on December 7, 2017
• Version 57.0.2, first offered to Release channel users on December 7, 2017

• https://www.mozilla.org/en-US/firefox/52.5.2/releasenotes/
• https://www.mozilla.org/en-US/firefox/57.0.2/releasenotes/

Thank you very much. That worked after the uninstall...How did I miss that? Duh! You ROCK, As they say on the street.