I received the same error while building a blu-ray dvd. The blu-ray object was the BlankHDMenu for me. Since I had it linked to video and audio, I re-rendered it with the same settings as the rest of the videos. I think I might of had PAL checked instead of NTSC, not sure if that was the problem or just a bad render. Either way after hours of messing with encore, the re-render solved the problem.