Your computer seems slow, nothing seems to be working right, you crash a lot. Perhaps it's time you gave your computer a simple cleanup.

Getting Started:

Windows gives you these tools to help your system run more smoothly — Disk Clean Up, Scandisk, and Disk Defragmenter (and I recommend using them in that order).

However, before doing any of this, it is advisable to be sure that all non-essential data is removed from your system, particularly tiny files (these clog up the space). Directories to check include C:\WINDOWS\TEMP, C:\WINDOWS\RECENT among others. You can also clear your browser cache and empty your email trash bins.

There are third party utilities to scan your drive for files of specific types (eg. files with 0 size, *.tmp files, etc. However, if you routinely clear your cache, history and recent lists, this is really optional. The tools provided by Windows should be all that you need.

Programs in the background may prevent scandisk/disk defragmenter from working properly, so before beginning, it is recommended to disconnect from the net*, turn off all virus programs, firewalls, etc. The easiest way to do this is to press CTRL+ALT+DEL and follow the instructions there to shut everything off but SYSTRAY and EXPLORER**.

However, even then, a previously unmaintained system may experience problems running scan disk/disk defragmenter, in which case I recommend powering down, and restarting the computer in Safe Mode. Most of your programs may not work in Safe Mode, because Windows bypasses your start up files, and many drivers will not be loaded. However, scan disk and disk defragmenter will both work in Safe Mode.

Running scan disk and disk defragmenter for the first time in a long time may take a very long time indeed, however, once done, the next time should not take nearly as long.

When should one defragment? This depends on how the machine is used. If you just log on to surf forums once in a while, or otherwise only use the computer moderately, once a week should be sufficient. However, if you are running 24/7, downloading 2-3GB per day, and visiting hundreds of web sites, the system can get bogged down, and will need more attention, such as every 3 or 4 days.

Another time to scan or defrag is when installing or uninstalling large programs. Installers create TEMP files and/or directories, and delete them when the installation is complete, however you end up with program data scattered all over the drive. Scan/defrag before and after installing a large program (eg. Microsoft Office, or a Corel Graphics suite) will help the computer run more efficiently.

How do I run these programs? Whether in Safe or Normal mode, these programs are found by hitting the Start Button, Programs, Accessories, System Tools - all three are located in this area. Start the programs one at a time. In the case of multiple hard drives, you have the option of whether to do them all at once, or one at a time. Generally I scan/defrag C D E and F drives at the same time, and the C drive by itself after a major crash, install/uninstall or CD burning session (where I free up a lot of space on the C drive after deleting).

Notes:
* External modem (cable, DSL) users can simply unplug the power to the modem.
** However, do not do this until you have made sure you are not connected to the net.