I had serious issues reinstalling an old version of OS X recently. The fact that Apple doesn’t provide proper installers for old versions of the OS doesn’t help. And although I saved several versions of the installers, none of them worked.
I ended up downloading an installer from a torrent site, put that on a USB stick an upgrade to the latest possible version form there. A real pita. I mean, sometimes one really needs to do a fresh install of an older OS. Apple should make that more easy.