I shut down my computer (which now has Lion, and has for awhile), and the next time I started it up it never gets past the grey screen with the progress bar. I tried holding down option and choosing "Recovery HD", so I can now type on this site . When I tried to verify the disk it, it checks the catalog file and it finds an "invalid sibling link." When I try to repair, it "Rebuilding catalog B-tree", but says it can't. Tried rebooting again but it's the same thing. I tried to reinstall lion, but when it asked where to install it the only option, my HD says it's locked and it won't let me choose it. I've tried booting in safe mode (holding down shift) but it doesn't do anything. Oh yeah, and it is a MBP from mid 2009, 17". Any help would be greatly appreciated, I have my PhD work on here and the data from today hasn't been backed up yet, and is very, very important. On top of that my 2nd year anniversary with my girlfriend and she wanted an iBook printed out of our 2nd year together, and I will lose most if not all of those pics and can't make it for her.