I had a problem with PXE booting Dell Optiplex 320's at our site and
using the Novell Imaging Environment. I'm running:
Netware 6.5 sp8
Zen 7 sp 1 with IR4 and the IR4 June 09 update.

The problem is that during pxe boot the machine locks at the imaging logo
screen and you must power off and back on to proceed.

In order to boot the 320's I had to add hpet=disable to the APPEND line
of my *.cmd files in /tftp/cmds. For example: z_auto.cmd looks like this:

KERNEL boot/linux
APPEND initrd=boot/initrd vga=0x314 pci=nomsi hpet=disable install=tftp://
splash=silent PXEBOOT=YES mode=2

I hope this information saves someone a few hours of googling!