1. check the sata cable, they like to come unpluged. My old system liked to do that.
2. make sure bios is set to boot from sata.

I'm sure you've probably already done that but it never hurts to check. What motherboard are you using? Sorry I'm not much help I'll try to think about it to day and see if I come up with any answers.

This will make future installs alot easier.
http://www.nliteos.com/