Right, _both_ bugs have that characteristic. But the first one (the fence-post) only happens in very particular circumstances; the second (the un-initialized variable) should have happened every time. What astonished me was not that there was a bug (which I can easily believe), but that it was one that would have happened _every time they ran it_. 'dcheck' has this list of disks compiled into it. (Oh, BTW, my fixed version now reads a file, /etc/disks; I am running a number of simulated machines, and the compiled-in table was a pain.) So I would have thought they must have at least tried that mode of operation once? And running it that way just once should have shown the bug. Or did they try it, see the bug, and 'dealt' with it by just never running it that way? Noel