Comment 22 for bug 19196

initramfs-tools 0.32 contains changes which we hope will alleviate this problem:

initramfs-tools (0.32) breezy; urgency=low
[...]
  * scripts/nfs (mountroot): New variable: NFSOPTS, default to
    -o retranfs=10, hopefully closes 12942. The can be
    overridden in the initramfs.conf file.
    Thanks to Oliver Grawert for testing this!

To test it, execute these commands:

sudo chroot /opt/ltsp/i386 apt-get update
sudo chroot /opt/ltsp/i386 apt-get dist-upgrade
sudo chroot /opt/ltsp/i386 dpkg -l initramfs-tools # verify that you have >= 0.32
sudo chroot /opt/ltsp/i386 dpkg-reconfigure linux-image-2.6.12-9-386
sudo ltsp-update-kernels

Please test this as soon as possible and let us know if the problem recurs.