I'm running W7 64 bit and when I connect an external HDD sometimes it shows and sometimes it doesnt. I work a lot with external HDD's plugged into one or all of my front USB ports and there doesnt seem to be any consistency to when it shows in the computer tree.
Between this and autoplay not working it feels like W7 has taken an enormous leap backwards. Just ridiculous.
This fixed it:
I had this same issue and it was driving me crazy!! I checked everything I could think of!! Until I thought I would check it out in the computer management..
Go to:
Control Panel
Admin tools
Computer management
Disk management
And sure enough there were my drives that I couldn't access. I had to right click on the drive header and select 'Online'
And now sure enough I see all my drives in the 'Computer'
From this thread:External Hard Drive Not Detected
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