Look on Western Digitals site for downloadle utilities for testing your hard drive. You can also run Chkdsk on a reboot of Windows (doubleclick My Computer, rightclick the "C" drive, choose Properties on the menu, choose the second tab labelled "Tools", the top heading is "Error Checking, click the Check Now button and checkmark both boxes then click Start.
Windows will tell you you need to restart your PC for the test to occur. Close your open windows and click the Start Menu program and restart Windows. Chkdsk will run during bootup and will report any bad sectors and will also attempt to remap bad sectors so that no files will be written to them.
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