I had nVidia dvd decoder running within MCE2005 very well for a month. The system had InterVideo dvd player/decoder as well, but not used. Yesterday, I noticed there was no tray icon for nVidia decoder while playing DVD. I don't know how but windows was using old InterVideo decoder, hence no nVidia decoder icon in tray. However, MS dvd decoder check utility still said nVidia decoder was primary and preferred decoder. I couldn't understand then why MCE and WMP were not using nVidia decoder. I decided to uninstall InterVideo dvd player to leave only nVidia decoder on the system. After uninstall, check utility showed only nVidia decoder which was good. Guess what. MCE2005 and WMP couldn't play DVD saying there was no proper dvd decoder intalled! How is this possible?