Apologies, I should have put more details in my first post. I'm running arch with LXDM (via inittab) and XFCE, not using a xinitrc file. I only seem to see the message during shutdown, and not anywhere else that I'm aware of. Luckily it doesn't seem to be harming anything, the system continues to reboot fine. I was more curious what it was and if it had potential to cause issues.