Hi, I have a issue with my iMac 27, it was very slow, long story short: I had to format and reinstall Mavericks. The problem is when I come to migration assistant: it does not allow me to migrate from the last mavericks backup. It says "the selected backup cannot be used for migration". In fact, I think the problems is that I tried yosemite for a couple of days and there is a Yosemite backup also on that TM hard disk. So Migration Assistant sees that Backup as a too recent OS, and refuses to migrate, regardless there are tons of Mavericks backups to use. I can't figure out how to tell migration assistant to discard the Yosemite backups. Should I just delete them? Thank you in advance Alex EDIT: I can't reinstall directly from the backup, as, in that way, the problem of being slow also "reinstalls".