what are the details of the computer you’re having problems with? brand/model
the first step i would take would be to update the undionly.kpxe file to the latest version from here
[url]http://sourceforge.net/p/freeghost/code/HEAD/tree/trunk/packages/tftp/[/url]
if that doesn’t work, try using undionly.kkpxe instead
there are plenty of threads about troubleshooting ipxe error 0x040ee119