So I have an odd, recurring issue with my TM disk. Early last week TM failed a backup, then again. so I naturally went to Disk Utility to try repairs. No go. What I got was an "invalid sibling link" and the repair failed. Many times. I then went to Terminal to attempt fsck from there. No luck in a repair, even after a dozen or more runs. I was able to finally get the TM disk to mount, but could not copy any data off. So its a reformat and redo the TM initial backup. All 18 months of my backups were lost. No huge deal, but it is sad to lose that much time from my time machine. Now I just got a machine. Last night the same thing happened. TM failed, and this time hangs the Finder when the backup action will not stop. Dock stops responding. Can't relaunch Finder, end up having to do a hold the power button down thing to reboot. DU returns the "invalid sibling link" thing, will not repair. Running fsck from the terminal now, but my hopes are low. [update: Terminal just returned it could not repair] Question here: is this a TM problem? Or, is this a disk issue, something with the physical disk? Or even the external enclosure? I have had disks fail before, sometimes slowly, but they were way more inconsistent and harder to diagnose. They were just "corrupt". I am preparing to purchase a replacement disk to install in the same enclosure, which BTW is a Lacie Quadra. My topology is I have 3 LaCie Quadras, all daisy chained with FW800 from my 2009 MacBook Pro. The TM disk is the first in the chain. The disk itself is about 18 months old, the enclosure 3 years +, and is the oldest one I have, and is out of warranty. The disk itself is in warranty. Never had any issues such as this, or anything really, from any of the Quadras or the disks. The only other thing different about this computer recently is CS5 Design Premium installation about 3 weeks ago. I do not think that CS5 is the root issue here, as none of my searches for info on this problem returned any CS5 note at all. Any insight here would be appreciated. Thanks.