The SC1894 and SC2200 cannot coexist on the same machine. Only one GUI can be installed at a time. So, if you have one GUI installed already and you would like to install the other, you will need to uninstall the other by going to "Add or Remove Programs" in the system settings and selecting "Uninstall." Note: for the SC1894 GUI, ensure that both the normal and advanced GUI's are uninstalled before attempting to install the SC2200 GUI.