i had same issue.
problem is, win 7 for some reason haven't assigned a letter for your hard drive.
here's how to add letter manually:
Open start menu, and in search bar type compmgmt.msc and hit enter.
This will open computer management tool.
Then in new window on the left side expand menu Storage, and click on Disk Management.
You should see all your disks in the center part of the screen
Find the 'missing' drive(the one that doesnt have name\letter), right click it and click on "Change Drive Letter and Paths"
Then click on "Add...", tick on "Assign the following Drive Letter", choose the letter you want, press OK, and close the manager.
Now You should be able to find your missing drive in "My Computer"
Aw man, i'm late, ain't I? D: