This is something I've wondered about for a while. When doing a defrag, there are always a fair number of files that are marked as not to be moved. They can be at the start of the drive, the middle or towards the end. So... why. What is it about these files that dictates they must stay put. Surely if all files were moveable, this would make the defrag process more efficient. But by having files that are fixed on the drive in this way must mean that other files then have to be positioned around them so to speak and must give the defragger more work to do. Anyone know why files get fixed like this.