When I try to boot OS X normally (or in Safe mode), I get the usual Apple logo plus the spinning gray circle of lines, but also a progress bar that never progresses. It either stays at that point or shuts down. When I boot in Verbose Mode, or run /sbin/fsck -fy in Single User Mode, I get output that looks like the following: Code: ** /dev/rdisk0s2 ** Root file system Executing fsck_hfs (version diskdev_cmds-491~1). ** Checking Journaled HFS Plus volume. ** Cheching extents overflow file. ** Checking catalog file. disk0s2: I/O error. Invalid node structure (4, 28704) ** Rebuilding catalog B-tree. ** The volume Macintosh HD could not be repared. /dev/rdisk0s2 (hfs) EXITED WITH SIGNAL 8 I've tried zapping PRAM and swapping out RAM, so I'm gueessing that means the hard drive is messed up. (Although I can still browse through and write to files in Single User Mode). Any feedback on whether my conclusion is reasonable?