I had an issue like this with the Don't Wake the Llama card table. My sims would start eating, but after a couple bites the card table would show up in their action queue, and they would stop eating and go play cards. If I x-ed it out they would also stop eating. If I started them back eating, it would just happen again. Needless to say I got rid of the card table. For some reason only the adult one did it - I was able to keep the kid one and the glitch doesn't happen with it. One of the weirdest glitches I've had in the game!