I was writing up my previous post and didn't notice yours and Marcs last couple of posts.

Long shot, but I noticed you are on a 550Mhz processor.Your project settings are DV AVI right? Your processor would struggle woth MPEG2 playback.

Don;t worry though, I am only on a 700Mhz processor myself. Whilst this a a bit of a pain for rendering, it does cope (of a fashion) with MPEG2.

Lots of things to try yet.

Let me know how you get on with the previous post.

Cheers!