I read Don's thread @ http://www.venturerider.org/forum/showthread.php?t=15376&highlight=surging.  In that thread he mentions "Surging", what would be the description of that.   
I run my mini Shuffle with a cassette adapter and it act like it changes sides when playing.  It will always keep playing but there is a pause about every 15 seconds or so.  Is this what Don is referring to?