Your registry may be full of rubbish.

What is the computers registry?Think of the registry as the central nervous system of your PC, it contains all the settings for every thing on your PC. It basically tells your PC how everything is too run. Registry is the core of any operating system and it is the proper functioning registry that determines how fast the computer boots up, launches applications and carries out commands. Whenever a user makes changes to Control Panel settings, file associations, system policies, or most installed software, the changes are reflected and stored in the registry.

The registry contains two basic elements: keys and values, this forms the core of the computer's operating system. Registry problems can occur for many reasons, including references left behind after uninstallation; incorrect removal of software; missing or corrupt hardware drivers; or orphaned start-up programs. 

Problems with the Windows Registry are a the most common cause of Windows crashes and error messages.  Every time you use your computer you change the PC’s registry, and with use over time it will become cluttered with useless data  and can fill up causing your machine to slow down.  These PC problems are usually caused when you improperly install/uninstall software.

There are a number of free scanners that can scan your PC's registry looking for incorrect settings and errors.They can even correct a lot of the errors found. Before you start blaming the computer and start replacing computer hardware, it is worth running one of these scanners before you throw away you PC.

If is safe to say that anyone of these registry cleaners can help optimize your PC and get it running fast again. A combination of registry errors and hidden spyware can make a once speedy machine seem pedestrian.