[gPXE] Press a key to reboot

[KernSafe Technology]

Hi,

I'm trying to install windows directly on a san, by following the article:
http://etherboot.org/wiki/sanboot/win7

I set bios startup order:
1, Network
2, cd-rom.

But after gpxe booted, it does not boot cd, but promote a message:
PRESS A KEY TO REBOOT.

This only happens on some computer, do someone encounter this problem before?

Aldrich.