One of my Macs (older OS, 10.6 aka Snow Leopard) comes up purple after reboot, requiring killing the client's xymonlaunch process (which launchd restarts, and then comes up ok). This is because the hostname isn't properly set yet.
I had a workaround that worked on other systems, but not that one, in the form of a modified runclient.sh script that took an additional option to wait until it could e.g. ping the xymon server by name before proceeding with the rest of what the script does, at which point the network would be up and the hostname set.
Looking at the Mac man page for hostname, I saw mention of a way to set the hostname that would persist across reboots: scutil --set HostName name-of-host
Did that, rebooted, and it came up fine.
That should probably avoid the need to hack up runclient.sh (and bring changes forward when updating). There might be undesirable implications for doing that on a laptop that was used on different networks, though.