[danieltillett]

I did a semi-clean upgrade. I bought the Mac Pro late last year and it stil had 10.9 on it. I upgrade to 10.10 before copying across my user files and software from my laptop running 10.9. I have been trying to figure out what the cause is by looking at the crash logs without any success. I do find that daily reboots lessens the risk, other than this there does not seem to be any rhyme or reason.

I have been using MacOS of various stripes since 1990 (I am a biologist by background and biologists were one of the few groups that stuck with macs through the late 90s). Other than 10.1 Yosemite is the buggiest OS 10 release to date in my experience.