em0 watchdog timeouts

[Rudy]

> Finally, while doing some comparisons, I realized that the motherboard
> having the problem was _not_ the same as the others; it was similar, but
> not identical.

This is a good piece of info.  I can try swapping out the MB and see 
what happens.

I do want to add: thank you Jack for all your help and if does turn out 
to be the MB, then double thanks.  Viva Monday!   :)

What would be nice would be MORE info for a watchdog timeout... maybe a 
sysctl dev.watchdog.debug=1 or something where when a watchdog event 
happened --- for whatever driver --- a bunch of stats were dumped 
relating to the event.

Rudy