dual displays 720p content exceeds in width

hi

i have my second dispay to the left and i use 2 x 1280x1024. Whenever i 
play 720p HD Content i get a bit of the window
on my primary display with a green color. Is it a bug or do i need to 
change something in my config? Or maybe it is windows or my graphics card...

/Matte

[mkv] Track ID 1: video (V_MPEG4/ISO/AVC), -vid 0
[mkv] Track ID 2: audio (A_AC3), -aid 0, -alang und
[mkv] Will play video track 1.
Matroska file format detected.
VIDEO:  [avc1]  1280x720  24bpp  23.976 fps    0.0 kbps ( 0.0 kbyte/s)
<vo_directx> adapter 0: Primary Display Adapter
<vo_directx> adapter 1: Matrox Millennium P650 PCIe 128
<vo_directx> adapter 2: Matrox Millennium P650 PCIe 128         <--
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
==========================================================================
==========================================================================
Opening audio decoder: [liba52] AC3 decoding with liba52
Using SSE optimized IMDCT transform
Using MMX optimized resampler
AUDIO: 48000 Hz, 6 ch, s16le, 384.0 kbit/8.33% (ratio: 48000->576000)
Selected audio codec: [a52] afm: liba52 (AC3-liba52)
==========================================================================
AO: [dsound] 48000Hz 6ch s16le (2 bytes per sample)
Starting playback...
VDec: vo config request - 1280 x 720 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
VO: [directx] 1280x720 => 1280x720 Planar YV12  [fs]