mount/umount hangs after I messed with /etc/mtab

[Krzys Majewski <majewski@cs.ubc.ca>]

I am unable  to mount/umount anything after messing  with my /etc/mtab
last  night (I  had removed  a floppy  without umounting  it,  and was
getting "Device  busy" when I tried  to remount/umount it,  so I nuked
the floppy line  in mtab, without backing it up, yay).  Now when I try
to mount or umount something, the command just hangs.  Any idea how to
reset  this? Renaming  /etc/mtab doesn't  seem to  help!  Neither does
rebooting! (Of  course, the box  won't shutdown cleanly since  it can't
umount  anything, although  for some  reason  it does  mount stuff  on
boot-up.) 
-chris