No scan was running and I watched ekrn.exe processor utilization and the file system stats in the Nod interface for a few minutes before I concluded it was not going to change. I am not sure how long it was this way before my user called me to investigate but it was at least 5 - 10 minutes before I got there and determined the problem and restarted the PC. Once I rebooted the workstation it started running normally again.