Please try the following:
-Try burning at lower speeds (Highly effective).
-Try using different brands of quality blank media like Taiyo Yuden, or Sony.
-Try upgrading your writer's firmware.
In the meantime, reinstall again the program and add again the files. You can reinstall the software from the next link: https://www.nch.com.au/components/burnsetup.exe
If you continue having problems send the information to: https://www.nch.com.au/support/