What do you mean by 'boolproped the kids into existance' (sic) ?
That doesn't seem right... the best thing to do would have been to use various hacks to either teleport them in (Ingelogical shrub or the puppy killer) and add them to the household or use pinhead's move in all hack.
Boolprop, although not the bane of evil that the sheeple make it out to be, seems kind of wonky when it comes to altering families, relationships, and aging.
Anyhew, I would suggest turning on debug mode (if you haven't already - boolprop testingcheatsenabled true) and trying to go to the lot and see if you get any errors from it when your sims try to deboard the vehicle. If you still get a freeze up with the taxi and no errors, I would suggest going into the dorm first, in build mode, turn on the buy mode cheat (boolprop dormspecifictoolsdisabled false) and place an FFS Lot Debugger module. Then, attempt to send your sims to college again, and see if the Lot Debugger detects any problems. You should be able to use the Lot Debugger to re-enable the save options (I think). If not, I'm pretty sure the puppy killer has those options. Regardless, you can also try the Lot Debugger to try and reset objects and see if that fixes anything.
Humor is great, but I suspect that patience is a better virtue to have when dealing with these problems.
Ste