Weird getty behaviour

[Juha K Kallio <juha@psychedelic.baana.suomi.net>]

For some reason, my gettys on tty2-12 aren't respawning correctly.
After I logout the shell (zsh, if it has anything to do with this)
the getty won't respawn as it should, but instead writes to auth.log
that the tty is in use. After switching to another tty with alt+fn,
it respawns after some time. 

Also sometimes, seemingly at random, some of the gettys on tty2-12 
won't start immediatly at boot time, but after a minute or so. In 
this case, they complain about I/O errors. This is naturally 
frustrating, as X might be started in one of these ttys instead of 
tty13. Neither of these don't happen with tty1, for some reason.