Starting with version 7 update 10, the Java plug-in has some new security options available. To access the Java settings, access the Java icon under the Control Panel and then click on the Security tab.
The initial checkmark option is to enable or disable the Java component within a browser.
The slider controls when a confirmation warning will be displayed. The medium security level will allow unsigned Java apps to run, but only if the Java version is considered secure. Setting the security level to very high will prompt the user for permission every time a Java app, signed or unsigned, attempts to run in the browser. If the Java version is deemed insecure, unsigned apps won't run at all regardless of what the user decides.