Dave VanHorn wrote:
>> The power is coming from a handheld computer, and is very clean and well
>> defined, so I don't think that's the trouble.
>Taking regged power across a cable is generally a mistake.
>Measure it at the chip, you may be suprised.
No cable involved, my board plugs directly into the computer (similar to
a PCMCIA card, and it's the same connector), but I'll double-check it.

>> Again, 3 boards work fine in exactly the same conditions, so it must be
>> something on this particular board.
>Or just a marginal design. Happens all the time.
Quite possible :-) But if so, I'd sure like to un-marginalize it...

So aside from power, what else could screw me up here? The resonator is
as close to the PIC as I could get it (less than 2mm to the pins), the
trace lengths are minimal, and the ground connection is solid, punched
right down into my ground plane next to the resonator.

>You might try lifting the xtal/resonator up a bit. Depending on the package,
>you can get a little crud caught under the package, which could be causing
>the problem.
It's a surface mount resonator (Murata CSTCC4.00MG if you care), and I
did replace it once, I'll re-solder and clean it up to make sure.

Thanks to all for the suggestions.

Dave Johnson