If you use the the HP iPAQ Bluetooth Stereo Headphones with an iPAQ hx2000 or hx4700 and are still running Microsoft Pocket PC 2003, HP has an update for you. The Bluetooth Headphones update includes one fix (enabling the the Pause and Next/Previous Track buttons to work properly with Microsoft Media Player 10) and some enhancements, the most notable one being the enabling of AVRCP (remote control functionality) for Windows Media Player Mobile.
Note: Make sure that your iPAQ hx2000 or hx4700 has ROM version 1.01 installed.
Source: Pocket PC Thoughts