The ship was 1 year old bulk carrier, UMS class with latest computer controlled monitors and devices. During sailing, one day early morning, M/E fuel oil viscosity high alarm came, the duty engineer went and acknowledged the alarm. On investigation, he found that the exhaust gas boiler steam pressure low. Local panel indicated low water and low/low water level alarms, but the control room panel did not indicate and also the alarm did not come. C/E was informed, bridge informed and the main engine stopped and on investigation found, all the economizer tubes had melted and wasted. It was also found that the alarms in control room for the boiler panel had been disabled. Somebody has infiltrated the computer system (though it had a password and only C/E was knowing about it) and had cancelled the alarm. Economiser was bypassed and the ship reached the destination port with auxiliary boiler firing.