SteveB:

Confirming - I took your code and loaded it into my 8720. It works as expected, except that it doesn't handle USART interrupts (as you mentioned). I'm thinking that your routine works better because you saved/restored BSR, while I was was saving/restoring FSR0L and FSR0H.

I have an email to MELABS. Maybe they can shed some light on this.

When we are done, I think we will have a good framework for how to deal with interrupts in the 18F series!