Francine,
In a similar
MacFixIt thread, Tacit had this to say re NAV:
"I would advise you to get rid of your Symantec antivirus program. Norton Antivirus, if that is what you're using, has a large list of very serious known and documented bugs; Norton Antivirus can cause kernel panics, system corruption, corruption of files on your hard disk, and problems with iPods and iTunes. It is, quite literally, worse than the non-existant threat it pretends to protect you from."
A search of the MFI forums yields many like comments and the horror stories that originally prompted the post.
Years ago, I used NAV. But now, I would not, under any circumstances, run a Norton product.