If it's not the sp mod, check any other mods you have if they're outdated or if you have installed the correct version to your set of expansions. Outdated/mismatched mods might cause some strange hiccups, some that don't seem to make any sense. For example, one mod I had the wrong version of caused everyone to catch on fire when they took a bath. It ended up being some social interaction tweaking mod that was causing it, something that had nothing to do with bathing :p