My MB at work got the pinwheel and crashed 4 times in a row today. I ran the Repair Disk in Disk Utility from the Leopard CD, and it failed because of an "Invalid node structure". The same thing happens when I run fsck in single-user mode. Now (later in the day), if I restart the computer, it goes past the Apple screen and turns off. Disk Utility via CD says 'Macintosh HD' is not mounted. The strange thing: if I go into single-user mode, all of my files are there and Macintosh HD is intact (Disk Utility still says 'Invalid node structure' in single-user mode). Similarly, if I hook up the laptop to my personal MBP via FireWire (to back up my files), I can successfully place it into Target Disk Mode, but the drive never appears on the host computer. Note: any searches into the "Invalid node structure" tell me to purchase DiskWarrior, but the computer is under AppleCare, and I'd much rather just send it in to them. The only problem is that if I do, I will most likely lose all of my data, so I still need to find a way to back it up. Any thoughts/ideas/comments? Anything would be much appreciated.