Obviously, it could be almost anything. To be sure that it is the Eclipse, see if it happens with the inputs disconnected. Also, see if any of the Eclipse controls affect it in any way. It's probably not a software issue.
Note that the Eclipse requires ALL pins of any used inputs and outputs to be connected as either signal or ground – they must not be left hanging in the air. You may have a bad connection on one of these – try swapping cables and see if things change.
