Just in case anyone else has the same problem - I thought i'd answer my own question.
The support people finally got back to me and just said 'try a different brand of disc' !!! I wasn't impressed.
I was also very unimpressed when I started to use the thing only to find the white on my screen very pink - and presumably all other colours were not as they should have been either.
It went back to the shop and I got a refund!