6vbonplh58b6 When you say you're playing on the lowest graphics settings, have you also disabled Advanced Rendering? It's a check box with the other settings. If it's enabled, disable it at the Main Menu, then quit to desktop before loading a save. It would be good to enable object hiding as well.
Additionally, were you playing this save when you had more expansions installed? Removing an EP from an existing save can and will corrupt that save. (Stuff packs are fine to remove, although you'll get missing objects warnings.) The only way to play without an EP you were previously using is to start a new save.
Aside from that, would you be willing to add a few mods? Whether they'd help depends in large part on the cause of the crashing—an in-game issue could be fixed with the right mod, while a graphics issue would not be. If you don't want to use mods, that's fine, but it's worth asking.