well, when he goes in his crate he might think that he you aren't comming back, so to teach him, let him go in his crate for about 10 minutes at a time while you are home...when you let him out, reward him by letting him play..do this alot..also about the biting i dont know what to tell you..but i did talk to a trainer at Petsmart and she said that she can train yorkies not to bite easily in one training session! you might want to take her to a class like that (they have private classes too..) if the biting gets worse.
