DVDs won't play when using dual video output sources

[MPalicki]

Have an XP laptop which normally plays DVDs fine through all my players
(Nero, Interactual, etc). But when I connect it to an external video source
(ie. LCD projector or S-Video out to TV), it won't play any DVD on any
player. Always gives some sort of error relating to something about an audio
codec. Any ideas?

 

[Cari \(MS-MVP\)]

What is the exact text of the error message?

 

[MPalicki]

it varies depending on which player I select. It either says something about
an audio codec missing, or tells me I need to stop any other media that is
playing or paused and try again. I think I found something on MS
knowledgebase that indicates this may be a known issue having something to
do with directdraw.