Error message saving to D Drive

I am trying to save a file to a D drive on my computer, and I am getting the following error message: "A required privilege is not held by the client." The computer is mine. It has always been mine. I have backed up the majority of everything, and saved it elsewhere. I have even saved some stuff on the D Drive. However, once again, I am being shown that I can't save anything on either my C drive or my D Drive. Please advise.