I am trying to install Sony Movie Studio but my registration code isn't working and I keep getting the red "X." This is for Sony Vegas Movie Studio 15 Platinum.
It's not Sony, but either VEGAS Movie Studio 15 or VEGAS Movie Studio 15 Platinum. Are you sure you have downloaded the correct program (bought from a reliable source) and/or that there are no typos in your registration details? Read also this thread just in case.