Maybe! It's definitely very odd seeming.
I've just reduced the error down to the follow behaviour:
I've declared a class:

   class RandomClass {
    public RandomClass(int a) {
   
    }
   }

Then, from just before the point of failure in my code, I've added a
call to this class:

 RandomClass rc = new RandomClass(1);
 aMethodCallThatIsUsuallyThePointOfFailure(.. stuff ..);

The code above executes the instantiation of rc ok and dies at the
second line.
If, however, I add another parameter to RandomClass constructor and pass
that in:

 RandomClass rc = new RandomClass(1, 2);
 aMethodCallThatIsUsuallyThePointOfFailure(.. stuff ..);

.. it now dies horribly on the "new RandomClass(1, 2)" line. Seems the
stack is getting corrupted or overflowed and the point at which the
program dies is merely a symptom of the real resource/corruption problem!
Thing is, this was all working fine until I did a tiny bit of harmless
seeming refactoring (I moved a class). Hmmm...

thanks for your reply!
lex