I'll start with the generic stuff:
1) Do you have anything on the drive currently or is it "empty"?
2) How long between dropouts.
3) If you open the waves in an editor, are they "about" the same length, or *are* they the same length?
4) How long have you had the device? (done any scandisc or other analysis on how good the drive is?)
I've never had that problem with mine, so I'm just mentally going through the first things I'd look at.