i just bought WD MyBook World Edition Network Interface and i start moving my movies/tv shows/music to it. Later that night, i start watching tv shows on AppleTV and suddenly the audio not sync with the video. I've tried on my iMac as well, almost 10 files, including movies and other tv shows and 6 of them not sync 
anyone ever experience this before? i've also tried backing up the same movies i still have to Data DVD, and still it's out of sync.
i'm sure that the movies and shows previously in sync, such shows like Friends, How i met your mother and downloaded Olympic opening ceremony etc etc.
some i don't have the original files anymore, but the one i still have is fine.
edit: i rip/convert movies/shows using Handbrake and VisualHub for AppleTV
pls advice
anyone ever experience this before? i've also tried backing up the same movies i still have to Data DVD, and still it's out of sync.
i'm sure that the movies and shows previously in sync, such shows like Friends, How i met your mother and downloaded Olympic opening ceremony etc etc.
some i don't have the original files anymore, but the one i still have is fine.
edit: i rip/convert movies/shows using Handbrake and VisualHub for AppleTV
pls advice