The things I have started to hate seeing these last days in my console:

localhost kernel[0]: display: Not usable
localhost kernel[0]: Previous Shutdown Cause: -72
localhost kernel[0]: HFS: Removed 27 orphaned unlinked files
localhost kernel[0]: Started CPU 01

My MacBook shuts down 10 times a day when I use it, and it's not being used for all day either - only before and after work. It shuts down 3 times only in a morning if I'm lucky, 10 times if unlucky, and it's getting really on my nerves.

I disabled the other processor with CHUD. Since that it has stayed up and running - except after waking up from sleep it did enable the processor core 2, and then it did shut down, so again the resetting PRAMs and PMUs it got up and running again .... now testing for a few days how well CHUD and disabling the other processor core keeps it up and running.

Every shutdown this computer has done - excluding only Mac OS X 10.4.7 system update, and installing Aperture and Final Cut, has been this previous shutdown cause -72. Every previous shutdown cause that I have bothered to look at my console, has had the line Started CPU 01 on the exact second it died.

I will follow this to see if it dies at all with the second processor core disabled.