Here's the deal.... I was doing work on my computer as normal and was in the middle of a file transfer between my Mac and a partition on one of my external drives. My external drive is separated into four partitions. Towards the end of the transfer, I got a message saying that what I was doing could not be completed and I hit "OK". The next thing I know is that the partition vanished. So at this point, I tried to eject the rest of the dive by ejecting the other partitions but then got a Kernel panic. I did what I was supposed to at this point. When I got everything back up, I turned my external drive back on but this time the partition that vanished did not mount. So I ran Disk Utility and it showed that that particular partition had nothing but free space. I already knew that everything was gone at this point so I went ahead and reformatted and will resume work like normal tomorrow. I'm just glad that I routinely back everything up... So anyway, I just want to know what happened. Could there have been a problem while writing a directory tree and it took everything with it? By the way, the rest of the drive is unaffected... for now.