Yah m8t, heard about this quite a few times... Work at Compaq's Customer relations.... anywho.

First time that happened it turned out the guy's daughter thought she would pretty up, her Disney cd with some stickers... Once it started to spin, the stickers came unglewed and blam... instant drive explosion. It's a good thing the faceplate didn't come apart as it kept the pieces from hitting the little girl. I saw the pics and it looked like someone put a cherry bomb in there.

Another time, the result was the same, but the cause was that the cd had been left on a window ledge and had a "micro" bend in it that turned into a crack.... when it spun up it started to wobble inside the cd.

It's pretty scary when you think about it, your spinning a plastic disk at extrem speeds. So imagine what will happen should something unstablize it.