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.".
Silverlight install#
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.