This is due to the motherboard having blown. The problem area is the 4 pin square power plug which powers the CPU. the problem is the cpu socket. The various parts of the board appear to be powered but other parts are not. Solution Replace the motherboard and power supply http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=260100093227&ssPageName=STRK:MESE:IT See the same site for the power supply too.
recover windows and all will be well.
Chrisf989
October 2007