GPT To MBR Conversion -> Windows 7 and Ubuntu

This is the problem if windows 8 is not uninstalled properly, there is a chance of leaving back some installation files in the drives. This will disable users to detect drives formatted using windows or ubuntu installation disks.

Problems will be as -
1) Windows 7 installed but not allowing Ubuntu installation.
2) Ubuntu will not detect formatted drives, windows installation drives and shows to re-format the complete hard disk by showing it as one complete hard disk size.
3) Either Windows or Ubuntu will be installed but not dual operating system.
4) The disk is of format GPT and will not allow reinstallation.

Solution for this is to clean the hard disk.

1) Insert Windows installation CD or bootable USB.
2) Navigate up to formatting disk drives.
3) When format is not allowed, come to install windows screen (1st screen in the process).
4) Press "shift F10 (or) fn F10" buttons.
5) Command Line (cmd) window opens up.
6) Enter the following commands -
      sources > diskpart
      DISKPART > list
      DISKPART > select disk 0 [The disk where you want to install OS].
      Disk 0 is now the selected disk.
      DISKPART > clean
7) Close the cmd window.
8) Continue installation process.