From your Windows menu select 'Control Panel' (or 'Settings→Control Panel').

Note: If you finish this and it still appears that Firefox doesn't have Silverlight installed, go to Firefox's Tools → Add-Ons menu, select 'Plugins' from the left, and make sure that Silverlight is enabled.

Uncheck everything except 'Cache,' and click 'Clear Now.' That's it you're all set!.

If you don't see a listing with checkboxes below, click on the black 'Details' triangle to show them.

Select 'Everything' for the time range to clear.

Start up Firefox again, and select 'Tools→Clear Recent History.' (If you only have one 'Firefox' menu, instead select 'Firefox→History→Clear Recent History…'.).

Click on 'Application Storage' and ensure that the 'Application Storage' checkbox is checked, and close out of Silverlight.

From the Start menu select 'All Programs→Microsoft Silverlight/Microsoft Silverlight.'.

When the download is complete, double-click it in your Downloads window, and confirm that you want to install it.Click on the install button, and save the file.Close up the Control Panel and start up Firefox.Answer any confirmation prompts, and allow the program to be removed.When it's done, find 'Microsoft Silverlight' in the list, and click 'Remove.' Be patient as the list of programs is filled in.Double-click on 'Add or Remove Programs.' If you don't see that option, click on 'Switch to Classic View,' over on the left.

From your Start menu select 'Control Panel' (or 'Settings→Control Panel').

If you're not sure whether you have Windows 7 or XP, there's a quick test: if you have a 'Start' menu button on the lower left it's Windows XP, a round button with a Windows icon instead of a word indicates Windows 7. These instructions will take you through the steps of removal and installation for Windows 7, Windows XP, and Mac. Updating Silverlight to the current version requires first removing any older version. You will have to quit the browser to follow the instructions, so you might want to download the PDF.

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