I own Vegas Movie Studio 14, and I've had it for a while now. Just recently though, whenever I start a new project and add any sort of visual media, both the preview and render shows up as black. If I open any old projects, it shows up perfectly fine in the preview window. I've already tried turning off GPU acceleration, pasting the project into a new one, lowering the resolution of my images/videos, and restarting both my computer and the application. I have an Nvidia GeForce GTX 1050ti GPU, an AMD Ryzen 3 1300X Quad-Core Processor, and I run Windows 10. If you have any other questions about my setup, feel free to ask.