heres a thought, is your motherboard using an Nvidia chipset? If so... Did you over clock the front side bus speeds? The reason I ask is I recently bought the latest and greatest shuttle PC, all nvidia, I overclocked (accidentally) it began acting very strange, displaying odd characters and eventually no post.... ended up taking it back and getting charged 20 bucks for something I would later figure out via web search. Hold the insert key down while booting (I think)... it's the only thing that will get your motherboard back to the correct FSB setting. That or slap an older slower processor in it under 1200... Resetting the CMOS does nothing... Apparently this problem isn't just experienced with shuttles... but anything using the nvidia nforce chipsets... and possibly other nvidia chipsets

That is if this is your problem....

Just did a bit of checking.. you do have n-force on that board.. try holding the insert key down... then set your fsb at a lower setting... I ended up having to use a lower fsb then what the system was supposed to be able to handle to just provide stability... I was kind of pissed, but it's still pretty damn fast so I don't mind so much