Exporting problems- Surround

Hi there. So I've edited my film, and my friend did surround to around 5 or 6 channels of audio. Sound effects, dialogue, music, etc.
Every time I export to master file, I export using Surround for all dialogue, sound effects, music, etc. yet when I watch it, there's a point where channels of audio missing and replaced with a loud clicking, almost like a machine gun.

Help?

Well, what are you using to watch your movie? Are you just watching it on your computer? Are you streaming it to a proper surround system via something like PS3 Media Server? I actually recommend PS3 Media Server but you need a PS3. You can export ProRes with uncompressed audio from FCPX and it'll play in perfect surround. You can also make great 6-channel .AC3 files in Compressor for use in DVD or Blu-ray authoring.