Joseph,

This may depend on the box you are using. On most of the boxes you will see
the key positions as OFF - SERVICE - ON or other labels. Some actually label
the console posistion.

The two events things to consider are, the console lock position on the key
will keep the CTRL-B from working, but not the CTRL-A (if memory serves).

Logging the console off after use is always a good security measure when
your computer room has traffic. This is of course the second event which
keeps folks from accessing some of the things they shouldn't.

Both these will leave the CTRL-A SHUTDOWN sequence available (once again,
this is from memory). As pointed out, the only way to disable this is to
unplug, or lock the keyboard as was suggested.

Beyond that, physical security is the best policy.

Not much help this time.

Dave