puzzlezaddict It happens with or without mods/cc. I moved my Sims to another EA-made lot, and it happened there too.
I tried with my computer offline, still happened, but I didn't disable the wifi, I will try that and report back if it makes any difference.
dxdiag attached.
Also, in case this is important, when I do go into build/buy (specifically), if they freeze, they/other things, like pets or Sims outside the house (Townies) still move around, and sometimes my Sims will complete a task in the few moments before they stop moving, like they normally do when you go from live to bb. I thought that was odd.