Yaris 2011 Squeal or Screech at Startup

[xqophx]

My Yaris hit 65,000 miles this spring, and then started screeching something awful immediately following startup. I figured it was the serpentine belt, so I had it replaced by Sears. Following that, the noise got worse and worse.

• It used to be just when the car was cold after sitting all night.
• Now it happens more often, but usually not when the car has been running or warm before startup.
• It is right after startup, I do not hear any other noises at any time.
• Sears is convinced it is not their fault.
• Sears wants to put the blame on my power steering.

I attached an .mp3 recording of the sound, which is double zipped so I could attach it here. ANY information is very much appreciated!