This script creates /var/run/screen, root:utmp, with appropriate permissions. If
that directory doesn't exist, non-root users can't run screen. This becomes a
problem if you remaster grml with a modified inittab that doesn't start any
screens as root.

Suggested change: add "80        -       S              
/etc/init.d/screen-cleanup" to
/etc/grml/fai/config/files/etc/runlevel.conf/GRMLBASE (but I haven't tested
whether this really fixes the problem).