How do I remove the question marks from the dock and put the current/correct program icons back. I know you can drag them off the dock and let go and they disappear, but as soon as I reboot my Mac they all switch right back. Some of these have done this since upgrading to Mavericks and then more since Yosemite. My Calendar, contacts, iPhoto, and VLC icons are all question marks now. There are also a couple programs I no longer use that are question marks too. But I drag them all off and have even put the correct icons in their place, but then reboot and it just reverts back.