As Time Machine is useless under Yosemite 10.10.1 in that it makes hourly backups but none of these are accessible for restore (restore key greyed out) should I bite the bullet, switch TM off, delete all my backups off my external HDD and start again. Do you think this will enable TM to work again ? I don't think I have anything vital in my backups anyway. Or should I wait until something/anything issues from Apple. Any advice, as always, is welcome.