Can't hear sound when moving in timeline or when viewing clip in Browser

Hi

Normally in FCP, besides using the wand I can move forward or backwards in timeline or when viewing clip in browser and hear the sound. Now suddenly I can't. It's happened before, and have no idea why it st ops and starts being available.

But this is the most bizarre version. When I switch to another app and then go back of FCP, I can hear the audio when moving using the arrows. But if I stop and move the wand elsewhere, and try and scroll using the arrows, I won't hear the sound.

Does anyone know how to make it work properly or why this occurs?

Royks