alrightie. now, i think i understand that filemaker uses that port 5003 (and a couple of others, right? 50003 and 50006?). the reason i put port mapping on the airport basestation was i wanted a particular computer (the "host" computer) to use the same ip assigned by the isp as opposed to it's private ip. i was under the idea that to do that move it had to be port 80 that i mapped, and that i just had to be sure that ports 5003, 50003, and 50006 were open.
i'm hope i'm being explicit enough about my thought, because i know that i'm screwing something up. if i'm wrong about any of that, genx, as it likely i may be, please let me know.
as it is, i won't have a chance to look at this issue again until friday of next week. thanks for the leads so far...