> another note: 
> 
> what's even stranger is if i put a halt right before and after the
> offending access, and just hit 'c' on the chevron the couple time, it works 
> (more or less) fine, and doesnt crash at all. anybody have an idea what is
> causing this? 

Would that be a timing issue on the much faster 600 machine (relative to
an MVII thingy)?  What happens if you throw in a few count loops just
where this happens, to give things time to settle?

Bob