&gt; As Jack says, you're probably dealing with a protection issue. What format<br />
&gt; are the videos&#63; Are they DVDs, mpgs, ...&#63; Are they commercially made or ones<br />
&gt; that you made yourself&#63; Are the ones that work a different format than the<br />
&gt; ones that don't&#63; What players have you tried other than Windows Media<br />
&gt; Player&#63;<br />
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Thanks to all for the questions.  Some answers and additonal details...<br />
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I have two videos, one .avi and one .wmv, that appear just fine on both monitors using Windows Media Player (WMP) under XP SP2.  Then I have other .avi files that show up on one monitor, but not the other.  WMP shows up on both monitors, but the window playing the video is blank on one monitor but not the other.  These are not DVDs.  The videos that do not work are ones that we made ourselves, while the videos that do work are ones that came with Windows.  Both videos that work and videos that do not are .avi format.  We have also tried VLC media player with the same results.<br />
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My latest theory is that HDCP is messing us up.  Perhaps HDCP content gets sent to the digital outputs of the DVI, but not the analog (VGA) outputs, which is all that goes out through the DVI-to-VGA adapter.  I did not know that HDCP could block only a part of the video screen (i.e., only the part of the screen containing protected content), I would like to have that confirmed.  I also do not know why videos that we made ourselves would be burdened with HDCP, while other videos from Microsoft are not.  I would like to know how to encode our own videos in order to avoid problems with HDCP.<br />
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I suspect we could fix this by replacing the dual DVI card with a dual VGA card, or with an adapter that converts the digital DVI outputs to VGA.<br />
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-- dkm<br />
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