I would recommend that you get in touch with the IRS. They will be able to tell you if there is an offset against your refund.
You can contact them through the information found by clicking here.
Or you can visit your local IRS office. You can find the closest office at the following link. Just click here and then click on "Taxpayer Assistance Center Office Locator".
You don't mention what state you are in so I can't give you direct contact information for your state. If you need to contact your state, look below and click on your state - this will take you to contact information for your state.