Fragmentation occurs naturally when you use a disk frequently, creating, deleting, and modifying files. At some point, the operating system needs to store parts of a file in non-contiguous clusters. This is entirely invisible to users, but it can slow down the speed at which data is accessed because the disk drive must search through different parts of the disk to put together a single file. Defragmenting moves files on the disk so that most of them are contiguous which speeds up data access.
1. Click on Start->All Programs->Accessories->System Tools->Disk Defragmenter
2. Select drive C: and click Defragment.
If you see the warning below try deleting some files and run the Disk Defragmenter again.
4. Wait while the disk is defragmented. This can take several hours.
