stevevnicks

it sound like its to do with driver signing in windows 7/8 ?, I think you will find that the line 6 driver is not a signed driver so windows 7/8 may block it. you need to make sure you allow windows to install the unsigned driver.
 
infact what O/S are you using ?? if windows ? what version?
 
for windows 7 try reading here this may help
 
 
http://en.kioskea.net/faq/3914-windows-7-how-to-install-unsigned-drivers
 
 
windows 8.1
 
http://revryl.com/2013/08/06/install-unsigned-drivers/