Hi. Thanks for your reply.
I am actually using Sony writable CDs (CD_r 700MB), I had a pack of 50 of these, and the first few I burnt were ok, but recently every one has been getting this sound on them. So, I wouldn't say these were particularly cheap.

I have been burning at 8 speed, so I will follow your advice and try to burn at an even lower speed and see what happens.

If this doesn't stop the problem then I don't know what else to do.
Thanks for your reply.