Microsoft Knowledge Base Article 883258 contains the following summary and introduction:

SUMMARY

After you install Microsoft Windows XP Service Pack 2 (SP2), a Bluetooth device that previously functioned correctly in Windows XP SP1 and that supported Bluetooth wireless devices may not function correctly. This article discusses how to troubleshoot:
• Bluetooth device detection issues.                               • Service detection issues.                               • Device detection and connectivity issues.

INTRODUCTION

This article answers the following questions about troubleshooting your Bluetooth device after you install Windows XP SP2:
What can I do if my Bluetooth devices do not function?                              What can I do if a Bluetooth device is not detected when I add the device?                              What can I do if I experience a slow connection with the Bluetooth device or the device is disconnecting?                              What can I do if some of the Bluetooth devices features no longer function?                              What are some things to consider if I have problems with my Personal Area Network (PAN) connections?                              What are some things to consider if a Bluetooth device cannot find its associated services?                              What can I do if my Bluetooth device loses its connection?