Why does my Sims 2 do this?

My normal Sims 2 plays normally but ponds flash red and almost a dark burgundy sort of colour. Which is fine because I don't like to put in ponds but when I install an expansion pack (eg: Pets), the walls flash that red and dark burgundy. But, if I put on Open for Business it doesn't flash. Why is this? Also, do you think it would flash if I put on Bon Voyage or Seasons? Thanks :)