How do you stop aggressive behavior?

  
Max

1256463
 
 
Barked: Sun Jul 1, '12 2:33pm PST 
Sarabelle growls, snaps, and barks at Max when ever he comes near her when she is getting attention! One moment she will be on the couch rubbing her face against us, then Max walks up and she growls and snaps at him! She does not do this with our other dog.We take her of of the couch and tell her no and stuff like that, but are we doing the right thing to stop this BAD habit? ------NEED ANSWER AS SOON AS POSSIBLE BEFORE SHE HURTS HIM!!!!!!!!!!!!-------