The New CSS Form buiolder 2 includes all of the functionality in Universal Email, Digital File Pro, HTMLEditor (or iRite) and validation toolkit.
if any of those extensions are installed, you will need to uninstall them before you install CSS Form Builder 2.
Go to the extension manager, and uninstall css form builder 2, If any of these extensions are installed, uninstall them as well:
Digital File Pro
HTMLEditor (or iRite)
then you can install CSS form builder 2 again.