Have a number of wav music files. However Sonic returns 'not recognised/ does not support' when I want to burn a CD of thos files, while at the same time listing wav files as ones it supports. What's causing the problem and how do I overcome it?

Could be a codec problem. Try installing K-Lite Codec Pack (http://www.free-codecs.com/download_soft.php?d=5562&s=775)