You could look into whether a driver update is available for your Alienware laptop. Also a Windows update/fix might be possible.
One example of an issue (with workaround) that stops certain devices working in USB 3.0 ports is shown at
http://blogs.msdn.com/b/usbcoreblog/...-3-0-port.aspx (That's for Windows 8.1 not 7 so probably not the cause of your problem.)
Also another issue at
http://us.focusrite.com/answerbase/c...-non-root-hubs
You could also try connecting the non-working device to your Alienware via a powered USB 2.0 hub.