I have a strange problem all my machines pxe boot apart from a hp 620 laptop which comes up with the error

TFTP.
PXE-T01: File not found
PXE-E3B: TFTP Error - File Not found
PXE-MOF: Exiting PXE ROM.

I am using FOG 1.2.0 on Ubuntu 13.10, bootfile I’m using is undionly.kkpxe (it’s the only one I could get to work with all my machines) and it’s a fresh install.