Comment # 8 on bug 943845 from Robert Schweikert

Using gdb did not work. When I tried to attach to the X server process the
whole system locked up. I waited 10 or so minutes to make certain I was not
being impatient but the system did not recover and I ended up doing a hard
reset.

I did confirm my suspicion that it is emacs related. After starting back up I
closed all the emacs sessions and then rebooted. The condition was not
reproducible, i.e. with emacs not starting automatically when I log in the X
server no longer pegs the CPU.