Game is freezing (but not crashing) when using page up/down function

Hi guys, long time player and wondering what the heck is causing a freeze so specific. My game runs absolutely fine until I try to switch between floors in my house (or the camera follows a Sim upstairs/downstairs) and suddenly it freezes. It's not a crash, I can alt out of the window and go back in and it'll be back to normal...only like, 10 seconds later, I have the same issue. I don't know what this is because it happened in the middle of playing, not on launching the game. Yes I have mods but so few (only three script mods). I've repaired multiple times. Any idea what could be causing this? I'm so sick of all the bugs in my save I'm ready, after 27 generations, to just uninstall the game and start from scratch ☹️