Bluetooth in xps m1330 is RUBBISH

But Why?

I have a Dell BT 355 module in my xps m1710 and it works beautifully with my Samsung SBH500 Stereo BT headphones.  I can leaving the music playing on my desktop upstairs and go down into the kitchen on the floor below and it still works mostly fine.

However my m1330 laptop is a different matter.  With the same BT module (Dell 355 BT) and the same headphones, I can't be more than a few feet away from the laptop before the music signals breaks up badly. Even sitting working AT the laptop it will stutter from time to time. And if I cup the headphone receiver in my hands it stops altogether (this test has no effect at all when I try it with the m1710). 

The m1330 laptop is powered by the mains adaptor and is running with Vista in High Performance power mode, but even so it seems the BT transmitter in the m1330 is just pants!  I have also tried a different BT module (the Dell BT 360 Bluetooth) and the performance is just as bad.

So what's wrong with the bluetooth in the m1330?  It can't be anything faulty with the BT 355 module because of the comparison tests I've run with the m1710.  So do I have an m1330 laptop with faulty bluetooth circuitry?  Or is the m1330 laptop just useless when it comes to bluetooth?

Thanks

NigelS