N360 Prem 22.5.5.15 Cant complete full system scan

Hi runnung N360 premier 22.5.5.15 on Win XP sp 3.  Norton appears to stop scanning before it completes a full system scan.  Has been doing this for months now and cant complete the scan.  Wondering if there's a limit to the number of files as it gets stuck at about 3.8 million over 3 drives?