another update. Didn't fix it last time around. Today, I tried every single spawn at that trigger and found 041delta to be the culprit. Edited it, still crashed, then just removed all groups and bingo, map works. So that trigger is now a non-spawn. fine. one of twelve is a freebie now.
done with this map. Still don't know why exactly that set of 4 AI groups caused it to crash. they were standard stuff.