Samsung SGH-A437 / A436

Hi! I have a 437, and have been having a problem when answering the phone. Upon answering a call, there is no Sound from the speaker and the mic is also disabled. I must press the center button 2 times to have things work. When i press the center button after answering a call, the emblem at the bottom of the screen changes from a speaker-to a phone-and back to a speaker the second time i hit it. It works fine after i hit the two buttons. Anyone know what the problem is and how i can fix it? Thanks!