> > Yes I am switching the battery with a switch.  I really hoped that
> > there would have been some sort of software solution, because I've
> > already got a bunch of PCB's made.

>         Have you tried adding a nice large capacitor in parallel with
> your switch.  Might help reduce the effects of the bounce a little.

Actually, my guess is that it would make the problem worse.  On quite a
number of micros with built-in power-up-detect circuits, the VDD voltage
must get down very close to ground before power-up in order to ensure that
the power-up circuit trips.  On many CPU driven devices, however, there is
not really anything to load down the supply once the CPU has stopped running.
As a consequence, devices' filter caps can sometimes hover around a volt for
quite some time, making startup unreliable.

A remedy for this which I have seen in a number of consumer products is to
use a SPDT switch; the common wire should go to the circuit's power-supply
input, one edge to the battery, and the other edge to ground.  Thus, when
the switch is turned off it will ensure that the power-supply voltage to
the chips in the device goes all the way to zero.  With luck you'll be able
to add something like this to your board (if you used a SPDT or DPDT switch
and left the other pins unconnected).