The partition table on the external hard drive must be set as an MBR (Master Boot Record) for it to work properly between Windows 7 or Vista and Windows XP. There are two ways this can be done: From Disk Management on a Windows 7 or Vista computer or by writing zeros to the drive, initializing it and formatting it with an MBR partition table.

Note: In order to change the drive from a GUID partition table to an MBR all of the data on the drive will be erased. Make sure that you have a copy of your data before you proceed with one of the steps below.

Disk Management on a 7 or Vista System:

1. Right-click on Computer and then left-click Manage. If Computer is not located on the desktop it should be under the Start Menu

1. Left-click on Disk Management in the left pane.

1. Right-click on the colored bar for the external hard drive you want to change into an MBR disk and choose Delete Volume.

1. You will be warned that deleting the volume will erase all data on the disk. If there is nothing on the drive that you want, click on Yes.

1. The bar should now be black and show the drive as unallocated. Right-click on the disk listing (Disk 1 in the image below) and choose Convert to MBR Disk

1. The drive will now have an MBR. Right-click on the black bar and choose New Simple Volume to format the drive.

Note: For information on how to format the drive, see the following KB: Answer ID 3865: How to

partition and format a WD drive on Windows and Mac OSX

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