horizontal lines on video playback

[Tbtf]

For some reason I get horizontal lines that go up and down my video during playback this happens where their is motion in the video like a fight scene or something of that matter. I have tried Plex and Boxee and both of them do not have this issue, Does anyone know why this is happening?

[davilla]

enable "vsync always"

[Tbtf]

Ok thanks, i saw that in the thread below but I can't seem to find that option in settings can you tell me where it is. Thanks

EDIT nevermind I didnt know it was called vertical blank sync, once i get harmony remote working bye bye plex.

[tslayer]

Settings->Appearance->Screen->Vertical Blank Sync.