GTX 570 tearing

So I had screen tearing with the 306.23 nvidia driver, and then reinstalled it and then it was fixed. Then the next day I had screen tearing, a noticable difference to the day before. I know it does not have to do with the settings, like v-sync, or anything. But I reinstalled it again and it was really smooth and no screen tearing. Anyone know why this is happening? Its with a GTX 570 by the way.