The following may also affect Vista 64 bit laptop installations.
Windows 7, 64 bit OS, may inadvertently put USB ports to `sleep' or into power saving mode even when the drives connected to them are active. This will appear as though the drives have stopped functioning.
Ralph Grabowski reports in his blog about the symptoms and the solution
http://worldcadaccess.typepad.com/gizmos/2009/11/64bit-windows-7-usb-bug.htmlThe basic correction is to turn off any power saving settings for all your USB ports.
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