Two days ago my MacBook (OSX10.4) crashed; VLC player froze when I was watching a tv show. I though 'no biggie, happens now and then' and hard-resetted my 'book. Tried opening the file again with Quicktime, again, computer froze up. Waited a couple of minutes, hard-resetted my laptop again. Only this time, the screen got stuck on grey/lightblue-ish screen during boot-up. Tried a lot but couldn't get my MacBook up and running again. Started up with the OSX cd popped in and went to Disc Utility. Mac then told me there was a 'Invalid Node Structure' and that 'The volume could not be repaired'. During a third or fourth start-up this changed to Mac saying there was a'sibling error'. I checked some sources online, figured out this should be something fixable. One possible option was Disk Warrior. Supposed to be *the* tool with problems like these. I replaced my malfunctioning HD, put an old HD in my MacBook, reinstalled OSX and put the malfunctioning HD in a stand-alone case and connected it too my MacBook. As we speak DW is busy rebuilding the directory but it has been doing so for over a day now. I've read online that it can take a couple of days though. My HD is 250Gb with 30Gb empty space when it went kaput. Now, there seem to be a couple of other alternative options. These lads talk about Tech Tool Pro - apparantly some other program that could help: http://discussions.apple.com/thread.jspa?threadID=1635594&tstart=406 Then there's a couple suggestions/methods mentioned online that either involve booting up in single-user mode and type some code (http://forums.macnn.com/90/mac-os-x/149925/help-invalid-node-structure-repair-fails/ ) or do something alike in Terminal: http://mahalkita.nanogeex.com/2007/09/28/how-to-fix-the-invalid-sibling-link- error/ Has anyone ever had their HD act up like this? Any experience/recommendations regarding the programs/methods mentioned above? I'm pretty new with Mac (used PCs for ages, switched to Mac quite recently) and I'm kinda at wit's end here :/. I was in the process of backing up my stuff, but there's a boatload of data on that HD that I hadn't archive yet. I apologize for any possibly vague/unclear choice of words; English isn't my first language.