Snow Leopard shutdown issues

I upgraded to Snow Leopard and a few days later when i went to shutdown my mac pro after i woke it up, i got the blue screen and progress wheel just spinning. After calls with Apple, running both long and short hardware tests, 3 snow leopard discs, a clean install, 2 upgrades, the tech gave up. The clean install was a bare bones install with no applications installed. I would now have to take it into a repair shop and pay for software tests. This is a one year old mac pro with apple care. I used Time Machine to restore to leopard, and all is ok.
Has anyone heard of this problem? I'm quit happy to stick with Leopard, but am upset that an apple software problem has to be fixed and paid for by me.
I assume if it was a hardware problem it would show up in Leopard.
Thanks

 

Hardware issues are paid by applecare at a repair shop. Software issues are dealt with over the phone. The fact that i couldn't solve the issue over the phone means i take it to a repair shop for more in depth testing and hopefully a fix. If there is no hardware problem, the repair people don't get paid by apple. I have to foot the bill. This came from the repair facility and the apple care tech.