Multiple PXE Installation at the same time

Hi all. I've setup a PXE server which runs perfectly. The installation
starts unattendent and all I have to do, is reboot the pc to log into Fedora
Core 4.

However, when I start more than one pc at a time (I have 80 installations to
make), the pc's obtain their IP address from DHCP, load the kernel into
memory, load the kickstart file and when they look for the ISO file (I
guess) it says: Unable to mount NFS Share.

But remember, one pc at a time, it work perfectly.

Well, any idea?

Yanos
System Administrator