The LiveUpdate feature in Symantec's Norton Antivirus product automatically downloads and installs new virus definitions as they become available. These definition files are stored on your hard disk drive and can consume a large amount of disk space over time. Older Symantec programs, even when configured to delete old virus definitions, may still retain leftover files. Since each new update is all-inclusive, it is not necessary to retain earlier definition files. Manually deleting these files will not only free up space on your hard drive but will keep older files from corrupting over time.
Click on the "Start" menu in the lower left corner of your computer desktop and select "Run" from the menu. Type "services.msc" (without quotes) in the open Run box and click "OK."
Scroll down the "Services (Local)" page, locate "Symantec Endpoint Protection" and click to highlight. In the upper corner of the screen select "Stop the service." Next, select "Symantec Management Client," click to highlight and then "Stop the service." This will turn off Symantec's LiveUpdate Administrator to avoid corrupting the program's engine updates. Leave this window open so that you can restart the services in Step 9.
Click on the "Start" menu again and go to "My Computer."
Double click on your primary hard drive -- in most cases, this will be "Local Drive (C:)."
Double-click the "Program Files" folder to open it. This folder contains all the programs installed on your computer.
Locate the folder within "Program Files" named "Common Files" and double-click to open.
Double-click on the "Symantec Shared" folder, which is located in the "Common Files" folder.
Locate the folder "VirusDefs" and double-click to open. In the "VirusDefs" folder, delete any numbered folders (for example: 20100919.003) as well as files with the ".tmp" extensions. Windows will not delete the .tmp files but will not delete the currently active definition folder.
Restart the Symantec Endpoint Protection and the Symantec Management Client which were stopped in Step 2.
Open the Symantec antivirus program on your computer and run LiveUpdate to ensure that the latest virus definitions are installed. To manually update the definitions, download the Intelligent Updater from Symantec's website using the link provided in the Resources section below.
Stop both "Symantec Endpoint Protection" and "Symantec Client Management" prior to deleting virus definition files. Failure to do so will corrupt Symantec's update engines.