Ken Hornstein writes:
> Having used it for many years, I am mostly happy with it; the right
> things almost always seemed to happen.  However, there have been a few
> times where the tty got into a weird state and required a reboot.  That
> sucked.  It happened often enough that I remember it, but never often
> enough that it was disabling.

Thats a "bug". Any system feature could be bad if implemented with bad 
bugs.

.pm