In recent months, the disc activity light is nearly always on. However, the disc itself is audibly active only a normal amount. This is a Dell laptop. The only time that the light seems to properly reflect disc INactivity is soon after the OS is started (from restart or shutdown), before a number of applications have run. I have disc indexing turned off. Active processes are many, including Norton Personal Firewall and Antivirus (though I've used those for years without this peculiarity). Any idea what's going on? Any advice appreciated.