Taking session from LE6.4 to TDM 5.3

[Silence]

Just wondering if anyone has encountered this problem before and might have a resolution:

I took a session created on my PC-based 001, PT LE 6.4 into a studio. They are running an HD system based on Mac and use TDM 5.3.

We could get all the session info up including track names, we could see the grid I had and we could see the audio regions placed on the grid. However there was no audio information in the regions. The files were definitely there on disc, we could play them in Quick Time, but the audio would not come up in TDM 5.3.

What does this sort of problem indicate?

That Mac/PC compatibility was unchecked when I created the session?
Does anyone know if you have to save down to 5.0 for these two version of Pro Tools to talk to each other?

Also, is it fine just to save the PT session icon to disc along with the audio files and that will load up on TDM, or is there a particular way I need to burn the session to disc (I'm on WIN XP Home Edition and have just used the native CD burning function).

Thanks for any help offered!