Hello Robert,
Did the computer crashed and restarted or did you just get an error message? If so what error message? Check if you are using the latest graphics card drivers. Try both studio and game ready drivers. Do you have enough space for the cache? Did the crash only occurred on this project or did it happen on different projects with approximately the same number of images in the past? After this happens can you please try to search for RealityCapture.log before opening the application again and send it to us?