Sound problem with iMovie 4.0.1


I have a camcord, Cannon Elura 40 and I had been using it with iMovie foe a while. However, recently I have not been able to import video into imovie correctly. The problem is the sound. When I imported, I could hear the sound from both the camcord's speaker and my MAC G4's speakers. But after importing, if I played a clips from iMovie, this was no sound. If I tried to make a iDVD, it said error in encoding audio.

It used to work fine. I tested on a friend's iMovie HD, it worked fine.

What is even stranger is that I could extract audio from a clip and show the waveform (don't know if if's correct though because I couldn't hear it).

Please help.