There are multiple causes that lead to problems using a defragmentation tool. The most common problems include the lack of available RAM or virtual memory, computer activity while the defragmentation process is under way, anti-virus software preventing the execution of the process, and a lack of available hard drive space. These causes can both prevent a defragmentation tool from initializing and interrupt the process once started.
The defragmentation process requires a lot of physical and virtual memory, so it is recommended to shut down non-essential applications while defragmenting. The best way to avoid this problem is to start the process when no user plans to utilize the computer’s resources. This also ties into the problem that PC activity involving storing or deleting data on the hard drive interrupts the process. Scheduling the defragmentation process to run during an inactive period can avoid these problems.
Defragmentation tools typically require at least 15 percent of hard drive space to be available. It is usually possible to create the necessary space by running the Disk Cleanup utility or removing unnecessary applications via the Add/Remove Programs functionality of Windows. The problems caused by anti-virus software can be avoided by shutting this software down before starting the defragmentation process.