[ubuntu_mate] iMac not shutting down or rebooting properly.

Hello!,

I have an old iMac, 2006 Core 2 Due 1.83Ghz, i915 graphics, that has the newest Ubuntu (Mate 16.04, in this case) installed. Everything works great except for the shutdown and reboot.

The machine displays a LONG list of things going on upon shutdown/reboot, but I can't read most of it and I just get the last screen, which has a bunch of stuff that I don't understand.

Does anyone out there have a clue as to what could be going on? Is there a way that I can capture that data that is scrolling by when shutting down?

Thanks,
RMFlagg