To switch to Microsoft Bluetooth stack on Windows XP with SP2 system, please follow these steps:

1. Make sure the Bluetooth adapter is attached properly.
2. Open the Device Manager. The Device Manager can be opened by right clicking on the “My Computer” icon and selecting the “Properties” menu option. When the Properties dialog appears select the “Hardware” tab and then click the “Device Manager” button.
3. Expand the Bluetooth Devices entry.
4. Right-click on the “Actual device” (Example: CSR USB Bluetooth Device) and select "Update Driver".
5. When the Hardware Update Wizard appears, Select “Install from a list or specific location (Advanced)” radio button and click on the “Next” button to continue.
6. On the next page select "Don't search. I will choose the driver to install" checkbox and click on the “Next” button to continue.
7. The next page provides the selection between available drivers. Select the first driver in the list and click on “Next” button to continue.
8. On the next page, click the “Finish” button to complete the installation.