Where is it? You will always see oxidation/reduction of your solvent or electrolyte (the "solvent window"). Also, if you put an organometallic complex in your paste, you will see that peak too.
Do a scan rate study, is it diffusing or stuck to your electrode?
I agree with Kyle, and I would also like to know if the peak is reversible. Does it appear in both scan directions? What are the values of the peak potentials?