Audition CC 2015 Muting Audio Files At Random in Multitrack

In the last few weeks, I have encountered a recurring problem. I make a weekly radio show with AA - it's a simple affair: one track for Music files, one track for Links and one track for idents/imaging.

When I have been working on a session, and having saved it  and closed it, Next time I open it again to continue working, on the show,  various audio files have been muted - My only option is to go through and manually un-mute them again. It will do it to any of the files, be they the larger music files, the links or the idents. It is not muting the actual track in which the files are positioned, but actually muting the files themselves.

Can anybody give me an idea why this is happening and how to solve it, please?

I run AA CC 2015 on a MacBook Pro

Thanks

DD

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