russell: yes, the problem always occurs on the third attempt. i know a dptr is being successfully loaded on this third attempt, but i can't confirm if it is the correct dptr. i have thought about introducing an lcd display to use in diagnosing (display critical values like dptr or contents of acc), but i wanted to try this forum first.

erik: (i hope i'm interpreting your response correctly.) yes, i know that the iap_pgm_data_byte routine (per the device data sheet) uses data storage locations (acc, dptr, r0, r1, sp, data that i want to store). are you suggesting that i protect the dptr and sp prior to calling the iap rotine? if so, how can i do that without using data storage nor code storage via iap? my guess is here that i didn't pick up on your hint. if not, please dumb it down (even more?-you're probably thinking). maybe you can guide me towards a document that digs deeper into whats going on during iap calls.

thanks for the replies.