I would suggest that you use the Line 6 Uninstaller located at the location below to remove your currently installed Line 6 drivers:

Windows 7/Vista  -  C:\Program Files(x86)\Line6\Tools -  Line6Uninstaller

Make sure to disconnect any of your Line 6 USB devices prior to starting the uninstaller. Make sure to only check the boxes at the bottom of the list that are related to the Line 6 drivers, and proceed to uninstall them. Once they are removed, restart the computer. Upon restart download the latest Line 6 Window Drivers from the link below:

Windows Drivers 4.2.5.1:

http://line6.com/software/readeula.html?rid=4399

Make sure not to connect your Line 6 USB device until prompted to so at the end of the installation process. After connecting it, make sure and look towards the Windows system clock for a notification that Windows has detected your device and has successfully installed the drivers before moving forward. If you do not receive this notification message, make sure to try reconnecting the Line 6 hardware to each available USB port until you have exhausted all available USB ports.

Once the drivers are installed you will need to install the Line 6 Monkey application from the links below:

Windows Line 6 Monkey 1.51:

http://line6.com/getrelease?rid=4618

Once Line 6 Monkey is installed launch it and apply any updates that are available until you have a green check next to each component.

After the UX2 and computer system are up to date, assign the UX2 as your computer's external sound card using the instructions available on our video tutorial at the link below:

Windows Vista - 7
http://line6.com/support/docs/DOC-1453