The reason it is doing that is because you need to Delete the previous partition when you are installing Windows. 1.Insert the Windows XP CD-ROM into your CD-ROM drive or DVD-ROM drive and then restart the computer. 2. Press anything on your keyboard when it asks you if you want to boot the disc. 3. Press F8 to accept the Windows XP Licensing Agreement. 4. Your previous existing Windows XP installation is detected, you are prompted to repair it. do that. 5. On this screen you will see your C drive in the middle of the screen and it will say something about partition. You will see an option to delete the partition by pressing D. Press D the next screen press L then enter. After deleting the partition you will have to Create a New partition. Press C to create then press enter when it tells you the size of the hard drive. Then you can formate the dick from there and you will be ok.