i'm still not sure exactly what was causing it, my best guess is that when a preplaced hatchery was killed the ai assumed it didn't have any hatcheries.
the solution was to create the hatcheries via triggers
UndeadStar -- Spoiler: there are no medics in that video
[03:18 pm]
UndeadStar -- this made me remember a line in the Broodwar manual static about medics "lengthening the expected battlefield life expectancy to over nine seconds"