Windows Server 2008 -> Computer Management -> System Tools -> Shared Folders -> Shares
I can set up a share for the root of the external drive, but I cannot access it from another computer on the network. On the other hand, if I set up a share for a subfolder on that same drive, I can access it just fine from another computer on the network.
In both cases, the file and share permissions are the same: file system security grants full access to "Everyone", and shared permissions grant full access to "Administrators". The only difference I can see is that access to the share fails when the target folder happens to be the root.
Access behaves differently on the local computer than from another computer on the network...
From the server itself, I can open Explorer and access the default share
\\ComputerName\C$ of the main drive, but not the shared root of the external drive
From another computer, I cannot access either. Specifically, if I try to access
\\ComputerName\C$ from another computer, I am prompted for a password, but despite providing the correct computer name, username, and password, I am denied access and it just keeps prompting me for the password. If I try to connect to
\\ComputerName\USBDriveRootShare, instead of prompting me for a password, it gives me a message "Windows cannot access
\\ComputerName\USBDriveRootShare You do not have permission to access
\\ComputerName\USBDriveRootShare. Contact your network administrator to request access. That's followed immediately by another dialog that says "
\\ComputerName\USBDriveRootShare is currently unavailable."