Comment # 4 on bug 991383 from Dr. Werner Fink

(In reply to Stefan Dirsch from comment #3)

After the update of the nvidia kernel modules and the nvidia X11 drivers and
the final reboot a bacl screen had happen.  I've debugged this by using `set
-x' and an `exec 2> /tmp/log/ 1>&2' before the xrandr call.  After reading the
log 
I've removed the fresh build nvidia modules below
/lib/modules/4.1.27-27-default/ and used symbolic links from the previous
nvidia kernel modules of an older kernel into the weak-update subdirectory
below lib/modules/4.1.27-27-default/.