When I connected this unit to my computer for the first time using a USB cable, the installation procedure was canceled before this unit could be used. How do I reinstall it? (The same thing happens when I connected it to other USB ports on the computer.)

Re-connect the USB cable. In some cases, the reinstallation wizard may not starts up. If it does, follow the wizard to complete the installation. If the reinstallation wizard does not start up, install the driver software again.

Pioneer DJ provides the latest driver software on its website support page. Get them from this page.