pxe boot fails with pxelinux.0 file from jaunty

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Using LTSP in jaunty, pxelinux.0 from syslinux 2:3.63+dfsg-2ubuntu3, client fails to boot,
my client has this ethernet chip,

eth0: SiS 900 PCI Fast Ethernet at 0xd400, IRQ 19, 00:0b:6a:5f:d1:5b

revert back to pxelinux.0 from feisty runs ok.

root@ibizerver:/# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 9.04
Release: 9.04
Codename: jaunty

root@ibizerver:/# apt-cache policy syslinux
syslinux:
  Installed: 2:3.63+dfsg-2ubuntu3
  Candidate: 2:3.63+dfsg-2ubuntu3
  Version table:
 *** 2:3.63+dfsg-2ubuntu3 0
        500 http://localhost jaunty/main Packages
        100 /var/lib/dpkg/status

system is updated, including chroot LTSP