So, just starting to get into these, and they just keep locking up on me...is there something that causes this? I'm checking up on them at least every hour and re-rezing a few each time.

What exactly happens to you?
I do not understand what you mean

Looks like a stack heap collision error or whatever it comes up when I'm near them. but essentially, they just get stuck is some spot and stop responding, just do a couple random poses that don't go with the furniture that they are on and other mossms take the same spot like they don't exist. This site will tell me that they haven't checked in if I leave them long enough, and i don't get my points when it happens

Maybe it's because of the lag of the place, it has happened to me in some sims, or maybe the enviroment fails, try to ask a recovery of the mosms that fail you, sometimes ask for a new one fix the situation, and try with others environments, I have one enviroment that fails me and I do not use it

I bought new land thinking it was that.

Ended up doing the recovery every time one locked up, and so far, no issues :)

Yeaah!!! :))