In reply to HeMa:
> I'm not using Premier Po, so just guessin' but have you tested by addin' the music to c clip and then compiled/rendered it?
> I seem to recall my old FCP did something similar, if it was still background rendering the clip...
If I knew what that meant I'd try it. The problem is the lack of a consistent outcome which makes diagnosis of the problem difficult. I'll try to have a look at your suggestion but the problem is that sme of the music doesn't appear to need this.
Thanks for the reply in any case.