Audion CS6 not playing on hd, only form portable hd

I have CS6 installed on my tower.  When I purchased it, I copied a backup on a portable hd.  A few weeks ago, I no longer hear anything coming out from the version on my tower (my speakers work perfectly for everything else).  But when I access the version I saved on my portable hd, the playback works.  I have compared the settings on Audio Hardware and Audio Hardware Mapping on both versions and they are the same.  Anyone have a clue?  Thanks.