TT Nav 5.21 BT GPS and Acer n310

Hi, forum newbie here!
Just updated the s/w on my Acer n310 to TT v5.21 and also splashed out on a new Bluetooth MkII receiver as my old one (the TT one with a silver top and magnet underneath) was having problems getting a strong satellite signal. Now I have nothing! Device is paired fine using Bluetooth Manager but when I start Navigator all it says is No Device. Any clues?? Without Navigator running, the connection to the gps device stays up fine, but when I start Navigator, it only stays up for a few seconds, then drops out, then comes back then drops out and so on. What am I doing wrong???

Eddie