trouble uninstalling norton antivirus 2003 for 360 ver. 3 install


Subject: uninstall problem:

What steps do I need to take to uninstall Norton AntiVirus when
I have the following error messages?

I began with:
Start->Control Panel->Add or Remove Programs

When I tried to uninstall Norton AntiVirus from my computer
the software failed to be uninstalled completely.  The message
I received was as follows:
Error 1921
Norton AntiVirus Auto Protect Service, navap.svc, could not be
stopped.  Verify that you have enough priviledges to stop
system services.

Then a message appeared as follows:
Add or remove fatal error

I need to uninstall Norton AntiVirus with a message that
it has been completely uninstalled before I can install
Norton 360 Version 3.  I have Windows XP Service Pack 3
(previously Windows XP Pro) on my computer.

I would greatly appreciate your help.
Thanks in advance.

P.S. The following is more information about navap.svc

Norton AntiVirus Auto Protect Service:
(navap.svc ?)
Handles Norton AntiVirus Auto-Protect events.
Status:
Stopping
Startup Type:
Disabled
Log On As Local System

Also, during the uninstall process for Norton AntiVirus
some files involved during the removal of files were
described as "quarantined."  When asked about whether or
not to continue anyway I pressed "yes."