It sounds like an obsessive compulsive disorder. Discuss this with your vet as there are medications that she can be put on to take care of this. Another thing you need to rule out is a thyroid problem. So if they have not done this- request that they do. It just takes a little bit of blood to test for it and they may as well do a complete panel as it does not cost mush more. (At our clinic anyway- so you may want to ask just to be sure). Here are some very helpful links to the psychological aspects of cats licking hair off.
http://www.vetinfo.com/cathair.html
It could be this- this is what I was talking about. If you found this helpful please remember to accept it.
http://www.vetsoftware.com/acvc2002-virga1.htm
http://www.thepetprofessor.com/articles/article.aspx?id=352
Edited by jwarder on November 12 2005 at 12:38 PM
If my answer was helpful please click the green accept button My answer should not take the place of a Vet's diagnosis when needed. Positive feedback is most welcome and a bonus-though not required-is greatly appreciated no matter how small.