see thread
http://www.mp3car.com/vbulletin/general-mp3car-discussion/32724-revive-5v-hd-fed-12v.html
on a side note i've killed like 2 or 3 pw-x series power supplies, cracked my touchscreen...and a harddrive yesterday
im sure i've killled other things but i cant think of them off the top of my head. its an expensive hobby.