To hear your nails knocking, means that you are trying to show how unhappy you are in very delicate way. The nails that are red and very dominant, means you will not have to work hardly. The dull, unhealthy or yellow nails shows the hardships the dreamer is going to have. The dream in which you have long nails and injure yourself or others with it, means that you will have to deal with you aggression, otherwise you will hurt others more than you think you could to do so. The long nails also are symbols of your desire to get what doesnt belong to you, or you simply have higher expectations from life, then most of the people you know.
Read more about dreaming of Nails in other dream meanings interpretations.