I am trying to back up my 12 yr. old desktop before I wipe out the hard drive and give it away. I have a WD My Book 500 GB external drive. I go into the “Backup” tab, but I don’t have the icon to click “Start Backup”. I only have “Pause Backup” (which I can click on) or “Run Backup”(which I cannot click on). Can someone help me please? I’m not terribly techie, but can usually figure stuff out. Except this one.