This is Norton's answer. Make sure you click on the plus marks to expand the threads and follow the directions for your EXACT product. This links is for numerous products.
I have Dell Dimension 8100 and am running WindowsXP Pro. I don't know if this is one problem related to a missing file, but when I try to update NAV, I get an error "LU1848:Couldn't create callback object" I have NAV2003. When I run Norton Windoctor, it doesn't correct 1 problem because it says, cannot access a necessary file "mscoree.dll"