When I boot my computer from an off state, it boots just fine. But if I do a restart, my machine hangs before the BIOS even comes up. I'm running a clean install of Windows 7.
How do I diagnose the issue? Has anyone else ever had this problem?
Do you have evidence that the OS actually relinquishes control of the machine?
I've had this happen (albeit on Linux), and it was related to the ACPI configuration, so one more thing to try would be changing the ACPI drivers (from your motherboard manufacturer, or the ones included in windows) or updating the bios.
I don't know how to diagnose it with any certainty, but my best suggestion would be to
I've seen anomalies like this before, and it's often fixed by just completely resetting the BIOS's little brain.