pcntl_fork() race condition?

I am using php 5.0.3 and I have a class that I fork, the class works
fine independently and is very memory efficent, but when I fork more
than one process php races and I get a process that takes up 99% of the
CPU, is there a way to determine why these processes are racing? If I
do 4 processes all 3 processes will complete and the last will spike to
99% 5/4 etc.. etc..