Unattended WON'T on some computers

[HpVaC]

I have a problem, i've made an unattended Windows XP cd, office 2003, winrar, all the basics, the thing is the dvd worked with 2 computers i've tested it, BUT right now i'm installing a new computer INtel celeron 1.8 ghz/Biostar mainboard/128mb ddr/ the problem is that my dvd isn't working properly, i mean it installs windows.. but it doesn't even add the local user that used to add on the other computers, any clue? anyone need to see my runonceex.cmd code? is it someflag requied or something? the computers i've previously installed were Intel celeron 466/P4 1.5, help please