AVR-Chat

You are describing a classic race condition.  I think Brian Dean is right on
the money where the problem is.  Race conditions are very hard to smoke out.
You need a reliable trigger - or, if that isn't possible, then a repeatable
test case (which is the same thing).  Since you have two CPUs the only way
to get it repeatable is to synchronies the clocks & reset.

Good luck...

-----Original Message-----
From: Dave VanHorn

Having a persistent problem that is proving resistant to standard debugging
tricks.
I'm hoping that talking it through here, will dredge up the problem.

...