I've got a friend's MacBook and am trying to fix it for them after it crashed last night. On start up nothing shows other then a plain grey screen. I managed to get the install disk to show up by holding Option while turning on the comp. Though this took quite some time for the comp to process. After finally pulling up the install screen I noticed that there was no hard drive to select as a location for the install to go. So I went through Disk utility to see if I could repair the hard disk; however, this has resulted in only a list of errors: Invalid Volume Header Invalid B-tree node size Volume check failed Error: The underlying task reported failure on exit 1 volume could not be repaired because of an error Any ideas of how to get the hard disk to read, or will this take an installation of a whole new hard drive?