Comment 15 for bug 505916

The new udhcp package that supports the -C (no client identifier) switch landed in Maverick, and it can also be installed in Lucid without modifications.

So it'd be nice if both affected sides (=the ones using the Windows DHCP server and the ones using dhcp3-server) tried the following solution. If it works for everyone, it could then be committed upstream.
(I'm not using udhcpc at all so I can't test myself, I'm just trying to help in finding a correct solution for this bug).

 * Download and install the new udhcpc .deb from the "Builds" section in this page:
https://launchpad.net/ubuntu/+source/busybox/1:1.15.3-1ubuntu1
For example, for i386 chroots the necessary file is
https://launchpad.net/ubuntu/+source/busybox/1:1.15.3-1ubuntu1/+build/1858801/+files/udhcpc_1.15.3-1ubuntu1_all.deb
(I've also uploaded it to https://launchpad.net/~alkisg/+archive/ppa if someone prefers installing from a ppa instead).

 * In /opt/ltsp/i386/usr/share/initramfs-tools/scripts/init-premount/udhcp, change the following line:
        if udhcpc -n -c "$clientid" -s /tmp/dhcp-script.sh -i $i $hostname_param $ip_param >/dev/null 2>&1; then
to
        if udhcpc -n -C -s /tmp/dhcp-script.sh -i $i $hostname_param $ip_param >/dev/null 2>&1; then

* Then, run
        sudo chroot /opt/ltsp/i386 update-initramfs -u && sudo ltsp-update-kernels
reboot the client and see if the problem is solved.