Upon boot of computer, I press any key to boot off of my Windows XP disk. The loading occurs, temp files installed, I choose to do an install, press F8 to agree to the TOS. Then a screen comes up stating for my to insert a full version of Windows XP Pro, Windows XP Home or Windows 2000 disc into the CD ROM and press ENTER. The disc IS in the CD ROM and it was what was used to boot the Windows installation in the first place. The disc IS Genuine with the holo cover and all. I've used it before to install Windows XP onto my computer with no problems before. However, this time it's being stubborn.