Not that I'm trying to discourage you from seeking help here, as that's perfectly reasonable, but have you written to Norton's own support? This is something they should be able to answer, even if it takes a couple of days to get it.
I suspect, as does
@rgd1101, that there is probably some arcane setting under Norton that is different on the one machine than the others, and once found and tweaked would make "all right with the world" again. I don't want to hear, "But I didn't set anything differently!," because that's truly not the point, these sorts of weirdness do sometimes occur sans user intervention of any sort. I cannot count the number of times I've run into situations where a "burp" during install left one setting that's typically unset still set, or vice versa.
Also, not that I like throwing money away, but at some point if this is not resolved to your satisfaction you need to ask is the stress worth it. I've chucked software because "the care and feeding" of same simply was not worth it - period.