WGA (Windows Genuine Advantage) was designed to poke around inside your PC to make sure you're not running pirated Microsoft software and to rat you out if you are.
The Cuebot-K worm spreads via AOL Instant Messenger, registering itself as a new system driver service called 'wgavn'. It carries the display name 'Windows Genuine Advantage Validation Notification', and runs automatically during system startup.
"Users who view the list of services are told that removing or stopping the service will result in 'system instability'." More...