Hi Scott,
1. Do you receive any error message when you connect the external drive to the computer?
2. Do other USB drives get detected in the computer?
Let’s run the Hardware and Devices troubleshooter to automatically try and fix the problem
Open the Hardware and Devices troubleshooter
http://windows.microsoft.com/en-us/windows7/Open-the-Hardware-and-Devices-troubleshooter
If the above step did not help then I suggest you to contact Transcend support regarding the issue.
You may contact them from the link provided below.
http://www.transcend.nl/Contact/CuTechsupport.asp?LangNo=0&Func1No=11&Func2No=183