Power steering's one of those brilliantly simple things that's almost impossible to break. I've never known power steering to deal with a computer, but then again, the newest car I've ever owned was a '91.

There is a belt involved in the system, but you would have heard the belt slipping while you were trying to turn.

Another possibility -- power steering fluid clumps up if it ever gets in contact with water. Because your car's fairly new, I wouldn't expect this to be the case, but it's pretty easy to stir around the reservoir and work out if that's the case, so it's worth eliminating.

That's pretty much all I've got.