Strange bluetooth device in HP presario b1226

Dear all,
I have got a problem with the built-in bluetooth device in HP presario b1226.

I'm using vista home 32 bit. From time to time, the system could not detect the built-in bluetooth device. I have tried the following solutions:

1. To restore the default bios settings.
2. To make sure the "bluetooth radio" is enabled in bios.
Strangely, sometimes the "bluetooth radio" option shows in bios, but sometimes it disappears!! Why is it that strange??
3. To remove the "HP wireless assistant" software.
One of the HP staff said that this software might sometimes interferes with the normal bluetooth device.
4. To uninstall and reinstall the drivers.
5. To download the new bluetooth module driver and to try to install it.
But this driver can't be installed because it says the bluetooth device is not detected.

I have tried to solve this problem but failed. The bluetooth device is still not detected by the computer, and is not shown in the device manager. Does anyone else have the same problem?? Can anyone help me?? Thanks a lot!!

 

why can't the bluetooth device be detected by the system (vista home 32 bit)....help!