WD My Book Issue

HD is recognized by Windows and correctly showing files in HD. Upon trying to access any of the files in the HD, slows to a crawl and locks up. Connected via UBS 2.0 on WIN 7 X64. No previous issues with the HD - always running smooth and fast. Rebooted PC and HD - and still same issue. Any help/tips would be greatly appreciated.

ave you tested the external drive with either bootable or windows WD DLG Diagnostic tools?