Changed from CRT to LCD monitor: now xine and gxine don't work (but mplayer does).

[Adam Funk <a24061@yahoo.com>]

I run a Debian testing/unstable system and use GDM and XFCE4.  I recently 
replaced my old CRT monitor with a Digimate L1715 17" LCD monitor that goes 
up to 1280x1024 resolution.  To get it to work, I modifed the monitor 
section of /etc/X11/XF86Config-4 from
       HorizSync       30-92
       VertRefresh     50-150
       Option          "DPMS"
to
       HorizSync       47-80
       VertRefresh     75
       Option          "DPMS"
based on the frequencies given in the new monitor's manual.  I also changed 
all the "Modes" lines in the screen section from 
       Modes           "1024x768" "800x600" "640x480"
to this.
       Modes           "1280x1024" "1024x768" "800x600" "640x480"

Generally, everything works fine.  But gxine (my preferred video player) and 
xine now display only a bunch of green lines where the video should be.  
(I'd link to a screenshot but the one I took didn't capture what I saw -- 
it just showed a black box where the video should be.)  Mplayer, however, 
shows the same video files; I got the same results with a few different 
formats.

I don't know much about X and have no idea how to debug this problem, so I'd 
appreciate any suggestions.