Comment 5 for bug 693151

Just installed Ubuntu 12.04.4 LTSP and the error persist. To solve it follow the steps indicated by Warren:

sudo aptitude install dpkg-dev libgtk2.0-dev intltool libglib2.0-dev libtool automake
apt-get source ldm
cd ldm-2.2.9/
wget https://launchpadlibrarian.net/110513396/greeter.c.1204
cp greeter.c.1204 gtkgreet/greeter.c
sh ./autogen.sh
./configure --prefix=/usr
make
cp /opt/ltsp/amd64/usr/lib/ldm/ldmgtkgreet /opt/ltsp/amd64/usr/lib/ldm/ldmgtkgreet.bak
cp gtkgreet/ldmgtkgreet /opt/ltsp/amd64/usr/lib/ldm/
ltsp-update-image