First, go back to My Information and check what state you chose as your state of residence, then check what you said when you were asked if you had income in any other state.
If you find no error there, then revisit your W-2s or any other income form you entered and check the two letter abbreviation you entered for he state. You can revisit those sections by typing W-2 into the search window on the upper right, hit enter, then click on the Jump To that appears. Edit each W-2 from the little summary you'll come to, to check the state part.
