DivinylsFan The "shiny oval rugs" are social jigs, invisible objects that denote the area where two or more sims are interacting so other sims don't path through them. These jigs are supposed to disappear when the interactions stop, but that sometimes doesn't happen when an interaction is interrupted, particularly when it's interrupted as you're reloading the save.
To delete them, click the ground of the lot, select NRaas > MC > Object Stats > Not Inventory, and flush anything with "jig" its name. If you catch one still being used, the sims involved may move to the side a bit or lose their current interaction but won't be harmed overall.