Well, I exaggerate.  Not explained.  Reproduced, and un-reproduced, and
reproduced again.

If my Mac's airport card is turned on when I first configure wi0, it works.

Until I turn the Mac's airport card off.  Then it starts dying, and
everything times out.

If I turn the Mac's card back on, and ifconfig wi0 down, and ifconfig wi0
up, the card recovers.

Both systems are in ad-hoc mode, if it matters.

Anyone have any clue what I'm running into?  It looks like, if I have
the Mac on, and shut it off, there's a delay during which, say, another
NetBSD box can come online, see the first one, and keep them both happy.
If either of them is off for a while, though, the other dies, and then
they can't talk ever again until the Mac kickstarts the network.

Either that or I'm really, really, confused.

-s