My apologies if this is in the wrong spot Mavericks downloaded without problems but I ran into trouble as soon as I selected my startup disk for installation. Early 2013 iMac 27/i7/16 gigs/Fusion. The original 1Tb hard drive. Mavericks declared that my drive was a Time Machine disk and could not accept installation. Of course it was NOT a Time Machine disk and never had been. I run an external drive for Time Machine. Anyone else experienced this problem? I would be grateful for a solution.