I would check to see if the service exists or is enabled on your system...
...go to the System Configuration Utility
then click on the Services
then look for the service Norton AntiVirus Auto-Protect Service
to see if it exists. Listing them in ascending order might help you.
If it exists, verfiy that the service is enabled. If it's disabled, enable it and restart.
If it doesn't exist, then I would try uninstalling it again, but instead using SymNRT
, obtainable here with instructions: http://service1.symantec.com/SUPPORT...&osv_lvl=&seg=
It may be that some files may have been left over after a previous installation of Norton, and not removed or overwritten properly.