Nick:
The stack is 1k deep and we use less than 20 bytes of it. I have checked!
Neil:
The Stack is in Idata 256 bytes max

1) I think to have heard that some Dallas uCs have a nonstandard stack, is that the case with your chip?
2) the "I get in trouble when ints are different priority" is due to one of two causes: a) insufficient stack or b) ISRs at different priorities using same bank.

so a couple of questions
is 1) above correct? If yes are you sure you apply the switch that select that mode?
2) are you coding in asm or C
3) how do you know "we use less than 20 bytes of it"

Erik