I received the "files cannot be moved" error on my MBP. I have used iDefrag on the volume in target disk mode yet I still received the error. I took a last resort and wiped all partitions and even tried fsck before that. I restore my Time Machine to a new OSX Lion install and still receive the same error. I could only partition my MBP in target disk mode, if I tried to do it on the MBP in Recovery mode, it will tell me I couldn't unmount the disk. Running iDefrag, I noticed that at the end of the volume are a few blocks with a Volume header. No matter how much I erase or defray those blocks seem to be unmovable. Should i contact Apple Care for a Harddisk replacement?