I am guessing this is a bad thing

I have an old style uberhood, so I think that means it's corrupted already. I think it's crashing and burning, which is a pain in the butt. Would this be a symptom? I had three gravestones by the phone when I took a sim to the community lot chapel I built in Riverblossom, made a mental note to move them to more appropriate places.

Since then I played the McGreggor household, who had the social worker repeatedly visit, try to lecture them, fail and leave. They have no children. I turned testingcheats on, and an error came up about the apartment nanny controller, hit delete on that and it stopped, but not after I'd gone through all of the "nuke" options on the batbox, one of which was "urnstone markers".

So after playing them, I remembered to move the graves in the chapel, went into it, and they were gone. Quit to neighbourhood without saving, had a sim visit the lot, still gone.

I think I can remember who the graves were, but I'm not 100% sure whether there were three or four, I know three for sure.

I'm going to have to restart this hood eventually anyway, but I wondered what people thought - if this is related to corruption, or is it a more common problem than that? I have nounlinkondelete.

Try and use the Hood Checker and if it ask where you want the stones to go pick that lot. http://modthesims.info/download.php?t=456523

You sound like you do have some problems with this hood and you say it is a uberhood so yes it could be corrupted for when it was made not all the sim info was removed for they did not know of them at the time.

Are you sure it was "nuke urnstone markers" and not "tokens"? If it was, it's normal that the graves would be missing:
http://www.moreawesomethanyou.com/s....html#msg233696
http://sims.wikia.com/wiki/Game_gui...Urnstone_Tokens
I suppose you have nounlinkondelete (http://www.moreawesomethanyou.com/s...hp?topic=2083.0) then it shouldn't be a problem, and you can always respawn the tombstones.

Aha, that was the one! Ooops. I should probably not go clicking random buttons, then. I have no idea whose gravestones were in transit. Oh well!

It's very hit and miss. Some play sessions I have almost constant problems, and then it runs without a hitch for months at a time. I suppose I ought to go in and make copies of all the buildings I want to save, which is my main issue with restarting.