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As the description says, my external USB mounts when I plug it on my W7 machine, but it doesn't show up in My Computer.

It's listed in Device Manager under External USB...but when I go to Disk Management, the drive's size is displayed properly but it has no letters assigned to it and when I right click it, every single option is greyed out

One thing I noticed, under Status it says "Healthy EFI system partition".

Now, given that the disk has been used by another user on OSX computer, could this be a formatting problem?

And if so - is there a way to access the files on this drive or do I need to plug it in OSX computer, dump all the files on the system drive, reformat the external drive to something more Win friendly and then copy the files back up?

I would really appreciate some other workaround than this manual copy format copy approach :)

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You might need to try using a boot CD like Hiren's Boot or Gparted to re-partition the drive. –  Moses Aug 27 '13 at 16:16

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