I've never hear of a drive showing up in my computer but not disk manager but I have heard it happening the other way around. Is it a usb device? Have you tried it in more than 1 port? Have you tried it in more than one computer (preferably a non vista one)? but if you tried to format it & it stooped then you won't be able to use it on any system until it is reformated. You might have better luck if you try to reformat it in an xp computer. Is it still under warrenty? If so then you might contacting the manufacturer about replacement if not you can open it up & stick it in a desktop if it is a full size drive & take care of it that way. If it is a smaller size form factor then you'll have to buy a kit to connect it in a desktop.

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