PMDG-747X Cargo flight to Lisbon

Two strange things happened during my flight from KJFK - LTTP (Lisbon)Main tank 2 and 3 total lost fuel and went empty. According FCM totalizer reading I have still 36,000 Lbs fuel. I thought It cant be a fuel leak unless both Tank 3 & 4 connected each other. I assumed tank readings were in-correct. (That was mistake . It turned out FMC was giving false fuel total calculation in Tank 2&3) No fuel left in tanks. FMC still showing after arrival at Lisbon I should have 26,000 Lbs fuel. NO place to go on ocean. I slowed down to 270 and in case flare out, I lowered the flaps and landing gear then, here we go...FLARE OUT. FL310 tried to glide to Lisbon. No engines and only main battery on. Five miles to Lisbon RW 03 I was holding the plane barely in the air. I landed short to Runway.( I assumed we got bad damage to plane, but crew survived)In mean time when I was gliding to Lisbon 747 started to turn GHOST on me. Before , I was landing short to runway, 747 appeared once more..Do you have any idea what happed in this flight??Sanal