|The post screen comes up prior to the OS loading so whatever the problem is, it has nothing to do with windows.|
What's the make/model of your motherboard? Or if it's an OEM system (Dell, Gateway/eMachines, HP/Compaq, etc), what's the make/model of the PC?
BTW, this is not a CPU or overclocking question...you'd probably have better luck in another forum. Try hardware or Vista.