Hi there
The most likely cause to your problem is the PSU, try a standard psu from another computer if you can, by the way you can alternative psu for your shuttle like this one
http://www.overtek.co.uk/products/fsp-250w-flex-atx-1uJust google for 250w flex 1U psu and ensure that it has suffient plugs to feed you hard drives and other items installed in your case.