Strange happening in 4.2bsd

[Steve Feldman]

One of our users had a strange thing happen yesterday.  She 'rm'd a
file, and suddenly the directory containing the file was truncated to
be zero size.  (Not even entries for '.' or '..'.)  She was not running
as root at the time.  Fsck remade the directory and reconnected the
files which had been in it.

Does anyone know what could have caused this?  Is there a known bug
which needs fixing?
			Thanks,
				Steve Feldman
				Tymshare
				ucbvax!hplabs!oliveb!feldman