Hello, I am using an iMac, late 2007, with OS10.8. Every few days I get an alert that Time Machine can not complete the backup, and the icon on the menu bar has the little "trouble" sign in it. For the rest of the day there will be no backup. When I start the Mac the next morning I can hit the manual backup command and it works fine; and seems to be ok with a regular backup routine all day, for several days. Then, the situation hits again. A mystery ! Any ideas? Thanks Dave
