I have a BT Mogo mouse for my Latitude D620 and no problems. I LOVE the mouse BTW. The BT in this laptop is definitely a separate board from the wifi.

I do have similar trouble as you when my BT/GSM cellphone is too close to the mouse. When the phone is in my pocket under the desk everything works ok, but it makes me wonder what its doing to my human bits.

Happy new year!