Sometimes after installing Linux to a PC, it's not possible to reinstall Windows exclusively to the hard drive, without first removing Grub from the MBR. Should this situation arise, there are a few different ways to fix it.
Here are a few different ways to remove Grub from a hard drive's MBR.
Using Linux
In Linux, you can use 'dd' to wipe just the MBR of a drive
Simply unmount the hard drive or use a Linux LiveCD
Then run the following command:
dd if=/dev/zero of=/dev/sda bs=446 count=1
If you want to remove the partition table, in addition to the MBR, use this command instead:
dd if=/dev/zero of=/dev/sda bs=512 count=1
Using MS-DOS or Windows 9x Floppy Disk
Load the command prompt from a MS-DOS or a Win9x floppy disk.
Then run the following command:
fdisk /mbr
Using Windows XP Install CD
Boot the Windows XP install CD
Select 'R' for repair
Select Windows installation & enter admin password
In the terminal run the following commands:
FIXBOOT C:
FIXMBR
Using Windows 7 Install DVD
Boot the Windows 7 install DVD
Choose the language and keyboard
Click Repair your computer
Click on the operating system you would like to repair.
In the System Restore Options, click Command Prompt.
At the command prompt, enter these commands:
Bootrec.exe /FixBoot
Bootrec.exe /FixMbr