Normally if you hand-edit a linuxconf-generated sendmail.cf
file then the next time linuxconf runs it insists on
regenerating the file (this might be considerd a bug by
itself, but is not the purpose of this report).  When it
does so it brings up a dialog to tell you that it is doing
so, and waits for the "OK" to proceed.

However, if you hand-edit a linuxconf-generated sendmail.cf
and then reboot, then when linuxconf runs from
/etc/rc.d/init.d/linuxconf it will hang.  I am guessing that
it is waiting for the "OK" to replace sendmail.cf but, of
course, is not getting it.