Can you post your XML file? If generated by LANDesk you can find it in the managementsuite\landesk\files map on your core server.
Also, i would recommend you to always tick the generalize box when sysprepping. It avoids compatibility issues when restoring the image om another type of system.
Make sure the unattend.xml doesn't have a variable (e.g. %ComputerName% ), this will certainly cause this error. And what Frank said about generalize is helpful.
Make sure the variables are all correct.
Make sure the admin password does not have non standard English characters or dashes.
From there post the unattend after removing any sensitive data.
Thanks for your responses.
Although I figured this out on my own yesterday, it was what Matt said about the %ComputerName% variable that fixed the issue. Does anyone know why I can't use this variable to set the computer name?
Variables are ok as long as the Token replacement occurs during the LanDesk imaging process, I mentioned the %Computername% error due to an issue when that variable is used in a straight up Autounattend install. There isn't usuall too much entered in at the specialize pass, so it was worth mentioning. Edit: the token replacement occurs in the <image jobname>.ini, which in turn injects the desired computer name in the unattend.xml file copied to the system during imaging.
my INI file reference for the %Computername% token:
REMEXEC40=ldrun tokreplw C:\unattend.xml COMPUTERNAME=%Computer - Device Name%