I have a 500 GB external USB hard drive (Maxtor) attached to my Vista desk machine which I use for backups.

I plugged it into my Windows 7 laptop and it said it wasn't readable and asked me if I wanted to format it.

I plugged it back into my Vista desk machine and it shows all the files fine.

What could be causing this and how can I get Windows 7 to recognize the data on the drive?

  • what is the file system on the external? do you use a program like truecrypt? – John T Aug 8 '09 at 21:54
  • both file systems are ntfs – Edward Tanguay Aug 8 '09 at 22:13

I had this same problem between a Laptop with Windows 7 RC and Desktop with Windows 7 RTM. It ended up being that the external drive was underpowered by the USB port on the Desktop. The solution was to use a USB Power Booster cable. The booster cable allows the USB device to draw power from 2 USB ports at the same time.

The reason some USB ports are underpowered for a lot of external usb hard drives is the fact that most of the drives use more power than the USB Specification states the USB port should support. The reason they work on some computers (I think most newer computers) is because the manufacturers go above and beyond the USB Spec for power output.

  • thanks, it turned out in my case that the hard drive was not readable on vista anymore either and had to reformat it, bad drive :-( – Edward Tanguay Aug 8 '09 at 22:13
  • The link "USB Power Booster cable" seems to be wrong. Can you update it? – Fulproof Nov 17 '13 at 9:47

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