No screensavers, file indexers, other scheduled tasks. There is a registry hack to resolve this. See links below. Since sorting introduces fragmentation, by design, reported fragmentation levels will be misleading. In other words, after defragging, Defrag.exe will still report high levels of fragmentation.
Backups are essential before performing any form of disk-maintenance.
There are some free defragmenters kicking around, but I haven't yet tested any of them. Error Defragmenting Drive . All Rights Reserved.