Hi Dick

What's probably happening is that your scan was saved as
a grayscale or RGB image. The problem is that the
background may look white to you, but is in fact a really
faint shade of gray. You normally can't pick it on a
monitor, but the printer will show it.

To eliminate your background you can try three things:
1)Preferred method is to save the image as a monotone.
2)Edit the image in photoshop or similar to ensure your
background is white.
3)Click on the image in Word, bring up your picture
toolbar and select your transparency tool. Then click on
the background of the image. This sometimes does the
trick, but you'll get more reliable results with the
above options.

Hope that helps,
Dennis.