Welcome to CF! Never stop learning
Originally Posted by BK_123
If you going to install Windows then there will be an option to format the hard drive before installing and most OS's will give you that option.
Originally Posted by BikerEcho
when i want a clean install, i just use the OS'es install CD.
Most OS'es has options to mess with the harddrive before installing the OS.
Microsoft, in their infinite wisdom, designed the install process in Kernal release 6.0 (Vista) and up to look at the physical drive and determine if Windows files exist. This means that even though you invoke the format command and tell it to install cleanly, it will still re-use core files because it is finding them on the "Quick Format"ed drive (only removes the File Allocation Tables... not the data). If you were able to corrupt the kernel files, you'll see this in action when you perform a reinstall without wiping the drive. The problems will persist in the new install.
SOOOoooo... you can only attain a true 'clean' install by wiping the drive first using Hiren's Boot CD or my personal choice, DBAN. Then it will truly be a clean install.