Very Strange Drawing Error

[Cags]

Now maybe i'm being stupid, but this is driving me really nuts...

 

Insert the following code onto a normal form and let me know if you see anything strange when you load an image. For the smart-arses amonst you, feel free to tell me whats wrong by just looking at the code :). Basically the images are drawing all wrong. I'm wondering if it might be a problem with using GraphicsUnit.Pixel.

public Bitmap SourceImage;

protected override void OnPaint(PaintEventArgs e)
{
e.Graphics.Clear(Color.Black);

if(SourceImage != null)
{
	for(int i = 0; i < 4; i++)
	{
		Rectangle bounds = new Rectangle(i * 60, 0, 60, 240);
		e.Graphics.DrawImage(SourceImage, bounds.X, bounds.Y, bounds, GraphicsUnit.Pixel);
	}

	e.Graphics.DrawImage(SourceImage, 240, 0, new Rectangle(0, 0, 240, 240), GraphicsUnit.Pixel);
	e.Graphics.DrawString("Drawn in strips", new Font("Tahoma", 12), new SolidBrush(Color.White), 5, 5);
	e.Graphics.DrawString("Drawn as one", new Font("Tahoma", 12), new SolidBrush(Color.White), 245, 5);
}

}

protected override void OnPaintBackground(PaintEventArgs pevent)
{
// avoid flicker
}

protected override void OnLoad(EventArgs e)
{
OpenFileDialog openDialog = new OpenFileDialog();

// load an image for demonstration purposes
if(openDialog.ShowDialog() == DialogResult.OK)
{
	SourceImage = new Bitmap(openDialog.FileName);
}

this.ClientSize = new Size(480, 240);
}

[Cags]

Well I've worked out the problem goes away if I specify the targets width and height (by using the overload that excepts the targetRect rather than x and y). This seems odd to me as if the source is that size I assumed it would make the target that size. Perhaps it's down to DPI if anyone can explain it please post.