I suggest PSU has failed. In addition to pulsing switch, CPU fan may work on its own. Generally this then means the motherboard as been also damaged. Sorry. I had the same problem, changed the PSU, cleared the cmos etc but it was not saved from the the great emachine graveyard.
Werbo
February 2006
check if the red slide switch on the back of the power supply is set hor 115v it may be set for euro