I Movie sound problem

Can anyone please help?
i have an iMac G5 PowerMac 2.1Ghz with 1GB memory.
Running Leopard and iLife 09.
I had an intermittent sound problem which is now permanent.
When I edit a project in iMovie everything is fine including the sound.
When I prepare it for iDVD there is no sound in the iDVD preview or on the finished DVD.
If I add music in iDVD that works fine but no soundtrack.
iDVD works fine as there is still sound on old DVD projects I have.
If I try to save as a QuickTime movie instead it seems to start saving okay and then the time band just keeps getting longer and longer and it never finishes.
I can however save it as an MPEG-4 video file for watching on my ipod and the sound is fine.
Could the problem be with QuickTime and if so, any ideas how to fix?

Many thanks,


Bob

There are a few rare instances where having Flip4Mac WMV Player and Perian installed can cause these sorts of problems with iDVD. You might try disabling them if you have them installed.

Thanks Chas but I have neither installed. You think other non-Apple plugins could be the problem?

Bob