Unstable stereo image on iPod Nano 2g

[rockchuck]

I just did a manual install of Rockbox--automatic install did not work.  I can access all the menus, and everything looks fine.  But when I try to play any files, no matter what format, the stereo image falls apart.  Each song starts fine, then the vocals sound like they are coming from an echo chamber and get progressively more distant.  Anybody know what's going on, and how do I fix this?
Post Merge: March 22, 2011, 09:53:12 PMSolved it myself.  Read a ton of posts re iPod Nano.  Finally realized that it had to be a problem with duplicate files.  iPod was trying to play both at the same time.   OK now.