I had a similar problem until I discovered that I needed to have an aerial attached to both lugs of the 6235 assembly. It seems that Bluetooth reception is favoured by the left hand lug (if you were looking at the adapter with the lugs at the bottom). As soon as I attached the antenna to this lug all my problems went away.
....just a thought.
Many thanks for that but no joy, this is doing my head in -
When I connect the iphone to bluetooth everything is fine until the computer tries to install device drivers which then returns an error of no drivers found.
Then if I look in device manager under other devices there will be a yellow exclamation mark against "bluetooth peripheral device"
I found this answer but it did not work for me -