Different results with DrawImage in Windows 7 vs Windows Vista/XP

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.NET2.0

Windows

.NET

Win7

graphics

I got a strange results using my software in Windows 7.

To draw my image I use following code:

protected override void OnPaint(PaintEventArgs e)
{
    ColorMap[] m = new ColorMap[2];
    ImageAttributes ia = new ImageAttributes();
    m[0] = new ColorMap();
    m[1] = new ColorMap();
    m[0].OldColor = Color.FromArgb(255, 0, 0, 0);
    m[1].OldColor = Color.FromArgb(255, 255, 255, 255);
    m[0].NewColor = Color.FromArgb(0, 0, 0, 0);
    m[1].NewColor = Color.FromArgb(mBlend, 250, 125, 114);
    ia.SetRemapTable(m);
                
    Graphics gdiGfx = e.Graphics;                
    //gdiGfx.CompositingMode = CompositingMode.SourceOver;
    //gdiGfx.InterpolationMode=InterpolationMode.HighQualityBicubic;
// 1-st.
    //gdiGfx.CompositingQuality = CompositingQuality.HighQuality;
// 2-nd.
    gdiGfx.CompositingQuality = CompositingQuality.HighSpeed;
               
    gdiGfx.DrawImage(mImg1, new Rectangle(0, 0, this.Width, 
          this.Height), 0, 0, this.Width, this.Height, 
          GraphicsUnit.Pixel, ia);
}

where my Image mImg1 is
mImg1 = new Bitmap(Width, Height, PixelFormat.Format1bppIndexed);
filled with 1.

I am playing with mBlend from 0 to 255.
If I use 1-st setting my Image is still gray when mBlend = 128 in W7, when in Vista/XP image is pink (Salmon color).
If I change CompositingQuality = CompositingQuality.HighSpeed; (2-nd setting) I can even get different colors (blue, green) in Windows 7.

When I change my Image from
mImg1 = new Bitmap(Width, Height, PixelFormat.Format1bppIndexed);
to
mImg1 = new Bitmap(Width, Height, PixelFormat.Format32bppArgb);
everything works fine.