The Benefits of a Clean Installation
What is a clean installation? And what are the benefits?
A clean installation is when you erase all existing files and reinstall the system. This way, you eliminate the junk in your hard drive and eliminate some hidden programs that could slow your computer. If you need to keep your files, you can back them up. After the clean installation, only the essential applications are on your computer, which will work faster and safer. You can reinstall additional applications as you need them. Make sure to have the registration keys for purchased apps. I recommend a clean installation if your computer is crashing all the time. But you should consider buying a new one if it has been used for over five years.
If you want to know more about it, here is an excellent article on Lifehacker: In Defense of the Clean Install.