This might be a memory problem, as DizMatt says.
I've just spent yesterday tracking down a duff stick.
One thing I discovered was the need to clear the CMOS on my Asus board.
If you do clear it, use DELETE to have a wee dive into the BIOS and set up your CDROM as first boot and Hard Drive as second.
Fire up your OS disk and use it delete your partitions and quick format before you install it.