that is strange. did you try selecting a different type under options when you export? did you remember to dither down to 16 bit if you are putting it on a CD (cause 24 bit won't work).
if that's not working, you could try something like i have set up. I have a tool that allows you to take files out of sonar and plug them into another program, in my case cool edit. once i bounce my final mix to track, i export that track to cool edit, do some last minute wav editing, and use cool edit to export it as mp3 or .wav, whatever tickles my fancy. if you would like that program to link the programs, i can send it to you.