Question : Problem: 1TB external USB Drive appears in My Computer but not in Windows Explorer

A 1TB Fantom HD shows up in My Computer and in Disk Manager, but does not appear in Windows Explorer. The HD is connected to a USB port on a PCI card in the computer.

Answer : Problem: 1TB external USB Drive appears in My Computer but not in Windows Explorer

If it shows up anywhere, it would show up in Device Manager first.  At least it is Disk Management as well.  What drive letters does he have assigned/mapped already?  I've heard of Windows only assigning certain drive letters to USB drives, and if he already has say a e: - h: mapped then it might be why it shows in Disk Mgmt and not MC with a drive letter.