I decided, with the encouragement of some folks on this board, not to give up on Pyrex. This morning I went into my local Tru Value store and bought another 9" Pyrex pie plate. I had a brief discussion with the woman who was helping me. After hearing my tale of woe she concluded that my shattered pie plate 'could have been a sign'. I didn't pursue the conversation. Instead, I took the 1-800 number from the back of the packaging and called customer service. The nice young man who answered gave me a much better explanation. He told me that my mistake was putting the pie on a cooling rack. Apparently, this more rapid cooling process 'shocks' the Pyrex and it shatters. He told me to take the pie out of the oven and place it on either dry kitchen mitts or dry dishtowels. He emphasized that they must the dry. Then let the pie cool and cut it while it was still on the dry cloth surface.
All in all, I think his explanation beat the hell out of 'it could be a sign'. He's also sending me a replacement at no charge. Nice guy--since I didn't even ask for one.
So, fellow chowhounds, this ends the peach pie disaster story. Thank you all for your sympathy and attempts to find an answer to this mystery.
Now we know.
PS I'll be baking another peach pie this weekend! Let's hope...