If you recently updated Java, ensure that Java is enabled and activated by following this procedure:
1. Start Mozilla Firefox browser or restart it if it is already running.
2. At the top of the browser, select the Firefox button (or Tools menu in Windows XP), then Add-ons. The Add-ons Manager tab will open.
In the Add-ons Manager tab, select Plugins.
4. Click Java (TM) Platform plugin to select it.
5. Click on the Enable button (if the button says Disable, Java is already enabled). Ensure that Always Activate is selected.