[F15] X server died unexpectedly

[Andrew Parker]

On Thu, Oct 20, 2011 at 3:07 AM, mike lan <lan.mike88 at gmail.com> wrote:
> I got "logged out " many times  while working on KDE , looking at the logs "X server died unexpectedly" ,
> switched to xcfe for now. wich works fine.

Could this be you problem
https://bugzilla.redhat.com/show_bug.cgi?id=720137 ?  If so, "killall
-9 X kdm" from a vt is the workaround that I use (every time I boot
up).