Norton Nightmare with XPs networked

My beautiful network (three XP computers) has just crashed. I have learned from a technician who really knows his stuff that the culprit is my blasted Norton Systemworks 2002. My understanding of this is fuzzy (which is why I'm asking y'all for help) but apparently there's some setting in the TCPEP stack which Norton changes from a setting of 15 to a setting of 11. When you put it back to 15, the network functions again. It's the location of this setting that I need help with... I *think* he said it was in a file with initials BP or BPI or something like that. Anyway, I know it's involved in the TCPIP stack. Can anyone help me locate this file? Thanks in advance, Taz
p.s. I'm a genuine newbie at this, so step-by-step directions to the location of this file would be most helpful.
p.p.s. In a larger sense, this discussion should prove generally useful for people struggling with this problem. Surely I can't be the only one who's run across this blasted little glitch.
p.p.p.s. my tech friend says that it's the NAV (Norton Anti-Virus) portion of Systemworks that changes this setting, and that the other parts of Systemworks won't affect a network.
p.p.p.p.s. If anyone is wondering about whether to get Systemworks or not, you can guess what my advice would be.