Verify that the computer meets the minimum requirements.

2.5" or 3.5" SATA I/II Hard Drive

USB Port: 3.0, 2.0, 1.1

Note: Hard Drive is NOT included. 

Ensure that you have securely connected the power adapter into the unit and have connected the power cord into a known working power outlet.

Access your device manager and ensure it is installed properly.

• To access the Device Manager on Windows 7 and Vista, click on Start and type in "device manager" then press enter.  Double click on Universal Serial Bus controllers.  Ensure that the USB Mass Storage Device is listed without any yellow question marks or exclamation points.
• To access the Device Manager on Windows XP, click on Start>Run and type in "devmgmt.msc" then press enter.  Double click on Universal Serial Bus Controllers.  Ensure that the USB Mass Storage Device is listed without any yellow question marks or exclamation points.

Try plugging the unit into a different USB port on the computer.