My Xerox Phaser 8560 makes non stop noise as though it is about to print or scan. It never goes to sleep. This has been going on for several days. I have tried turning off and on and unplugging. The machine still prints, but the noise is relentless. I only get one error which says to unlock the scan head and turn the power off and on. I have done this several times and when I turn the machine back on it resumes its relentless noise.