objects bumping into other objects causing problems on the sim?

So I bought this scripted cat that walks around and will usually turn around when he bumps into something. I logged in today to find him returned to me along with all his toys saying that it was messing up the physics and causing problems on the sim...upon asking for specifics I was told that it was because the cat and his toys were bumping into things and that was messing up the physics and other stuff in the sim...

anyone understand this or have more information about this? It sounds to me like you can't set anything to physics and have it bump anything else without messing up the sim? Sorry for my less than technically apt brain, I'm just trying to find out why this is suddenly a problem as I have had the cat for months.

any insight would be welcome!

Objects rapidly bumping into each other cause major problems for a sim, particularly if the objects are complex shapes. Probably what happened is the cat walked into a wall and didn't turn around, but just kept bumping into it -- this would have caused the sim to slow down greatly.