-Download the latest version of DVC2 and update the firmware which can be found in the tools application available in the software directory and windows start menu
-Connect your interface directly to a USB socket on your computer, open tools.exe, select the "test" tab and move the faders, do you have the same problem?
-Has it always done this?
-Try on a different computer
If none of the above fix the issue, PM me the serial number and I will set up an RMA