ENTER RUN LEVEL crapola

[thad at cup.portal.com]

Three times in the past 4 months, when selecting "SYSTEM SHUTDOWN" from
the ua window, the system would "seem" to go thru all the normal procedure
in preparation for powering down, then, all of a sudden, either the
"ENTER RUN LEVEL (0-6,s,S): " prompt appears, *OR* I find myself (not root
and not privileged) sitting at the "#" prompt cd'd to "/"

WTF does one DO under such brain damage?

I just powered down and said "to hell with it" and, so far, no ill seem to
be boding, but WHY did it happen in the first place?

The /etc/inittab and other system stuff appears identical before and after
such brain damage.

Systrem config: 3B1, 67MB HD, 2M RAM on motherboard, 1.5 Meg RAM on one of two
of the EIA/RAM combo cards (installed in slots 0 and 1), and the tape
controller installed in slot 2 (the rightmost).

System software is 3.51 (not 3.51a).  installed software includes the
Development Set, MS WORD, and other misc items.