I suggest you uninstall both programs, download ImgBurn
, and try burning with that.
If everything works, then your installation of Nero or DVD Writer must've been corrupted. If you still want to use either one, uninstall ImgBurn (suggest you keep using that though) then install either Nero or DVD W. Not both.
If even ImgBurn doesn't work, something could be wrong with your drive; you may need to have it checked.