With every kernel since 3.11.10-34.1 my computer boots, but then randomly
reboots. I can't predict when, but usually within 15 minutes of boot. Ie. boots
ok, then at some time in the next few minutes: screen goes black and computer
reboots.  Subsequent reboots tend to mean a random reboot is faster.   

With the most recent update that I tried an hour or so ago, I seemed to be able
to provoke a reboot by using:

pip install pillow

At the time pip was missing the development packages, so I'm not sure if it's
related (pip downloads the source code for pillow then attempts to compile it). 

When installing old kernel versions other needed packages are not properly
calculated as dependencies (eg syms, xen and devel kernels).