Have you tried this -
Error: "Could not initialize NAVAP device. Unable to get drive status"
Situation:
When Norton AntiVirus (NAV) Auto-Protect loads, you see the error message "Could not initialize NAVAP device. Unable to get drive status." When you open the Event Viewer, you see the error message "NAVAP - unable to determine the location of the virus definition files."
Solution:
To solve this problem, try each of the solutions listed below until the problem is solved:
NOTE: These solutions assume that you are familiar with, and have necessary rights to use, some of the advanced features of Windows NT. If that is not the case, then contact your network administrator.
Check the Event Viewer. In some cases, additional error messages that point to the cause of this problem will be logged to the Event Viewer at the same time as the error messages described in this document.
Verify permissions. The user must have full control rights to the hard drive.
Run Windows NT diagnostics. Make sure that the hard drives are not reporting zero bytes free.
Run Disk Administrator. When it runs for the first time, Disk Administrator generates a new signature. This may resolve the problem if no signature was created previously.
Start NAV to ensure that the user interface loads. If it does not, then uninstall and reinstall NAV.
If you have a hardware RAID, confirm that the controller is not locking the drive. (A hardware RAID uses a separate controller card.)
Open the registry and navigate to the following subkey:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Servic es\LanmanServer\Parameters
Increase the decimal value of IRPStackSize to 11
For additional information, see the document Error: "Failed the Call to NAVSTATInit" and "Unable to Get Drive Status" when Loading Auto-Protect.
Confirm that a Temp variable exists and that it is pointing to a valid folder. Delete temporary files.
Make sure that the swap file is large enough and that, if it is not a fixed size, that there is enough room on the hard drive on which it is located.
Open the registry and navigate to the following sub-key:
HKEY_LOCAL_MACHINE\Software\Symantec\Shared Defs.
The following entries should be present, and pointing to the same valid directory:
NAV_50_QUAR
NAVNT_50_AP1
NAVNT_50_AP2
NAVNT_50_NAVW
If none of these solve your problem, then uninstall and then reinstall NAV.
Taken from
here
Also if you have recurring problems with Auto Protect take a look at me post
here
Edit scratch part 2 of my post as it appears you have NAV 2001.