Digital camera artifacts? What is this?

I noticed this pattern in one of my pictures and want to know if it's a common type of artifact (and what is it called if that is the case?) or if there is something strange going on with my camera or technique. The camera is a Canon S3 IS.



Original 2.5MB image can be viewed at http://home.cc.umanitoba.ca/~umsefton/IMG_0223.jpg

a bit more info on the picture. Were you shooting through a screen? What was the situation/scene like?

It's not your typical digital artifacting. It's not even bad moire.

I was shooting something that was relatively brightly lit. No screen or anything. Look at the full image if you want.

That looks like something wrong with the camera. It's like every second line of pixels is unscanned.