I often try to render a sim to mplay only to have Houdini crash some time in. It's always this same report.. does anyone know what's going on/how to fix?

ryzen 9 7950x
radeon rx 7900 xtx
128gb ram

Without seeing a hip file, I'd guess you ran out of physical ram or your overclock is set too agressive. Try rendering to disk, not MPlay. It holds every frame it rendered in physical ram and can build up over time.