Norton anti-virus

The suggestion from Symantec is to get the latest upgrade. NAVCE 7.61 Build 37b or above:

"Scheduled scans are immediately interrupted with the message "Scan stopped by user"
Symptom: A scan is scheduled and the computer is turned off. The computer is left off until after the scan is due to run. The computer is turned on and the scheduled scan starts, but is immediately interrupted with the message "Scan stopped by user."
Resolution: The scheduled scan was starting before the NAVCE servicewas fully initialized. The code was fixed so missed scheduled scans are not started until the service is fully initialized."

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The below is specifically for NAV 2000 :

Situation:
You want to know why Norton AntiVirus (NAV) stops responding while scanning the boot record or before scanning files.

Solution:
The inoculation database is corrupted. To solve the problem, delete the \Ncdtree folder and rescan the drive. Deleting this folder and rescanning the drive forces NAV to recreate the inoculation database, which will remove the corrupted entries. If you have more than one hard drive or partition, then delete the \Ncdtree folder from each drive and rescan.

To delete the \Ncdtree folder:

1. Locate the \Ncdtree folder:
2. Click the Start button, point to Find, and click Files or Folders. The Find: All Files dialog box appears.
3. In the Named box, type: Ncdtree
4. In the Look in box, select C. If you have more than one drive, then select All local drives.
5. Click Find Now. One or more Ncdtree folders appear in the lower half of the window.
6. Right-click each Ncdtree folder, and then click Delete. Confirm the deletion, if necessary.
7. Start Norton AntiVirus, and then rescan all drives.