forking off in php

hello, I have what may seem like a small problem but its not obvious to me. I have a script that I forked and that part works fine, it forks, tells me the pid like I wanted, and keeps running. Well, the problem that was not apparent to me until about 3 days ago when I was wondering why the script(my php chat server) was crashing at seeminly random times. I finally figured out that when I logged out of my shell in linux, the talker would go down as well. Obviously I don't want that but what do I need to add to the line when i start the script thanks matt ps If it helps, I am running php 4.3.10 on slackware