Do you remember how fast your computer ran the first time you used it? Compare it to now, isn't there a marked difference? It could be that there are simply too much junk on the system.

As you install more applications and subsequently uninstall them, you'd think that's the end of the story. But very often, this is not the case. When a program is uninstalled, there is a high chance that there will be files related to that program which are left behind on the system. These files are useless because the program is no longer there to use them, yet they take up space and clutter up the hard disk.

Not only that, there are settings left behind by the program that still reside in the Windows registry. The Windows registry is a system database used heavily by Windows. When there are errant or obsolete entries in the registry database, Windows sometimes get bogged down, or problems may occur. You may also have experienced cases where an uninstall ended with an error, simply because of an errant entry in the registry. But where to find the entry?

Most of these problems are caused by bad programming habits by developers. The developers sometimes forget that certain settings and files need to be removed when their program is uninstalled, thus these settings are left in the registry and the files are abandoned in the system. This is despite the user doing a proper uninstallation.

On top of that, sometimes this is done on purpose, especially when a user installs a trial copy of a piece of software and subsequently decides to uninstall it. The developers of that software may decide to place certain settings in the registry in order to prevent the user from installing or using the software again after the trial period is up.

You can use a third-party program to clean up the Windows registry in order to tidy it up and make sure it's in a good working condition again. Such a program is called a registry cleaner, and there are many in the market. You need to choose a good one for your system.