Bad Food Combinations - Yogurt and Fruit is one,

1. Fruit after a meal. Natural Hygienists have known for a long time that fruit doesn’t combine well with other foods. The reason is that fruit contains simple sugars that require no digestion. Thus, they will not stay for a long time in the stomach. Other foods, such as foods rich in fat, protein and starch, will stay in the stomach for a longer period of time because they require more digestion. So if you eat fruit after a meal, the fruit sugar will stay for too long in the stomach and ferment.

http://www.mindbodygreen.com/0-3615/10-Common-Food-Combinations-That-Wreak-Havoc-on-Your-Health.html