My 2009 iMac is starting to go slow and lock up, I've got my install disk that came with the machine, but when I try to install it, I'm told it's too old. I've followed some tutorials that tell me how to start over, but I get a message about not being able to unmount my HDD
Oh, and like a genius, I don't have a time machine backup from before Yosemite
Oh, and like a genius, I don't have a time machine backup from before Yosemite