I used to get that after ripping Norton out by the roots.....in those days before the Norton Removal Tool.
It was then required to go into the registry and search for the file name of the offending dll or vxd file. Then remove those lines from the registry.
If you don't know how to access your registry or search it for file names, you should seek help from someone well versed in those endeavors.
For me, that always stopped the error messages on boot up.
Good Luck,
The Doctor
