@JessOfRVA I can think of a couple possibilities, one of which is that the instance of whichever world is crashing may be corrupt. Inside the folder for a given save is an .nhd file for each world that has been played within that save. That file contains the data for that world as it's been played: the sims' ages and whether any have died or immigrated in, whether and how much the tombs have been explored, any changes you've made in Edit Town, etc.
If you delete the .nhd file for a world and then your sims travel back to that world, a new instance of that world will spawn, with the world itself in its original state. Doing so may eliminate whatever issues are causing the crashes, although you'd also have to start from scratch with the tombs. But that may be a better outcome than never being able to travel to that world again.
You can always experiment: remove the .nhd file, and if it doesn't work out, quit without saving, delete the new .nhd file, and put the original back. If you do want to try this, it's also a very good idea (although not technically required) to add a few mods, specifically NRaas ErrorTrap, Overwatch, and Traveler. After all, there will be a lot of stray data from relationships and sims that don't exist anymore to clean up.
If this doesn't help, please quit without saving, then try sending your sims to a different WA world instead, and let me know how it goes. The other possibility is that something about this save or the sims in it is corrupt, which is why I asked if these same sims could travel to a different world.
