Did that second recommendation ever work?
[FONT=Consolas]I am experiencing this problem in Ubuntu 12.04 Desktop (package: tftpd-5.2-1ubuntu1). The tftpd daemon does not start when the computer starts up, even though the tftpd-hpa job starts. As far as I can tell, the problem is that the tftpd service is starting before the network is properly configured. The problem seemed to go away when I changed the line
start on runlevel 
in /etc/init/tftpd-hpa.conf to
start on (local-filesystems and net-device-up IFACE!=lo)[/FONT]