Please help ZG5 wont boot correctly

Hey whats goin on guys, iv had my one ZG5 for a while now, iv messed with xp pro, micro, windows 7, ubuntu, and OsX.... Recently i had one partion running ubuntu and i was happy but im not really good with linux and i got fustrated so i desided to just go back to xp micro. i have a ASUS external dvd drive, i have used it many times so i know it is working correctly. The install cds im using are tried and true so i know they are working. I turned on the computer with the Xp disk inside. hit f12 and t it listed 1.hdd 2.network 3.cd..... i chose cd like usual and it keeps saing.......

for realtek rtl8101e/8102e pci-e ethernet controller v1.05 (071227)
client mac addr:001e3340135b guid:25e68c70-2205-11dd-a70e-001e3340145b pxe-e53:no boot filename recieved

pxe-m0f:exiting pxe rom.
no bootable device--insert boot disk and press any key

Even if the hd was wiped it should still boot from cd... it reconizes my cd drive in bios but once it tries to boot i keep getting that message... my next idea was going to put ubuntu on my ipod and try to install from usb so atleast i get a working machine... thank you very much and sorry it was so long.

 

Ok so it booted from my ipod and i reinstalled ubuntu 9.04...... but im still having the problem where i cant install anything from my external cd drive it acts like its about to then grub starts.. this has never happend to me before and iv done this tons of times, whats different now? its really fustrating, thank you