Thanks for the above answer, it worked for me. The other way is to quickly delete the problem recording before the preview box starts to play. So, fast on the fingers, arrow to the problem recording, press blue and press green as soon as you can. This should catch and delete the program before it starts to play in the preview. Its worked for me several times. If this doesn't work then use Martyn's solution above which also works.
Terry Henshaw, November 2008