i have a similar problem but my started after i dropped the phone. I have done a hard reset with no luck. I have to send mine back...its weird cause i can make calls and the vibrate works, but no sound or speakphone at all.
ROM date: 07/22/06
Radio Version: 1.03.03.10
Protocol Version: 32.34.7010.01h
ExtRom Version: 188.8.131.52