It just looks like it is underexposing them for some reason.
You can use a noise reduction program to make them better. The Daily Digi had a post about them (
http://thedailydigi.com/category/com...ps-and-tricks/)
Have you played with the modes outside where there is more light? Mine get all grainy like that when I don't use a flash or I have my shutter speed way too fast. Are you trying to use an action mode on your camera? Kids are hard!
Hope something helps!