You could try to restore the registry using scanreg/restore.
However the following might be associated with your problem when a SYMTDI.VXD file is giving problems
The Steps are:
Uninstall NIS 2002
Install NIS 2003
When the NIS 2003 Install asks you to reboot your system select "NO".
Then Select Start > Control Panel > System (if you have Classic
control panel view selected)
Start > COntrol Panel > Performance and Maintenance > System (if your
COntrol Panel is set to Category View)
Select the Hardware tab and click on Device Manager.
In the Device Manager window that opens click on View > Show hidden
Under Non-Plug and Play Drivers Select SYMTDI
Right mouse click and select properties.
In the SYMTDI Properties window select the Driver Tab
In the Startup Section select type as "Automatic"
Close Device Manager
Close Control Manager
Select Start > Turn off Computer > Restart
This time the computer will reboot without the error.
Norton Internet Security configure program will now run to setup NIS