Not too long ago I ran a program that was supposed to free up hard drive space by getting rid of extra language packs and ppc binaries. Everything looked peachy, I freed up 2 gigs of space, until I tried to sync my iPod nano and Mac OS just wouldn't recognize it. It will also not recognize my external firewire drive that I back up to. Is it possible for me to reinstall Mac OS and preserve my user settings and applications, or better yet, is it possible for me to just repair mac os somehow?