No sound from iMovie clips in viewer

[Ninetoes]

I can not hear any sound from my imovie clips. They are all stored in my iphoto library and function perfectly when I open them in iphoto via quicktime or if I drag them into the project pane of iMovie09. There is no sound however, when I hit space bar or skim over them in the viewing pane of Movie 09 and no action from the the green equaliser bars under the preview area. I have looked through all relevant settings and there is nothing obvious wrong - not muted etc.
Everything was working perfectly when I used iMovie a few weeks ago.
Any ideas?......
Driving me nuts!

System
imac os 10.6.4
2.8Ghz core 2 Duo
4GB 800 Mhz DDR2 sdram

 

[annieness]

sound

I'm having the same problem except when I skim over the movie I DO have sound. There's a little icon to the right of the green lights (for sound waves) you were talking about. If you click that it turns the skimming sound on/off. However, I can't get regular sound when i'm playing the movie!
Frustating!