It seems like you might have filed a Form 1099G last year. If you have not filed, you can simply delete the form by following these steps:
1. Sign into your account, select Take me to my return
2. To your left, select Tax Tools, click on the drop-down arrow
3. Select Tools
4. Under Other helpful links, choose Delete a form
5. Scroll down the list to locate the Form 1099G, select Delete and Continue with My Return
6. Try to file again