Just a stupid question: did you install the update released end of May? It solves quite a lot of audio problems.
Thank you, Lily. Yes, it is updated. It solved many audio issues but, alas, not this one.
This is a long shot, but you could try copying and pasting all of your slides into a new instance of Captivate. If you have specified certain audio settings Captivate should pick these up when you export. If not then it is possible that your CP file has become corrupted.
If that doesn't work, please file a bug report using the web address I have included below.
It would be interesting to see if the CP team can shed any light on why this is happening.
Best - Mark