Hi Andrew,
Sounds to me that it could be caused by 1) corrupt B2 software - the SD Card, 2) OR a Hardware problem with the B2 or 3) OR trouble with the WiFi
To eliminate 3) first, could you first try and play the radio though the B2 and see what happens.
If that still freezes or does not work, please remove the WiFi Dongle and drive your machine with the Front Display or the remote to play music and see if it freezes then.
If it DOES then the next elimination would be 1) the SD Card. - Ask Paul to send you a replacement.
If a new SD Card does not clear the issue, you will need the B2 replacing.
Fred