What was found
ROUTE DISCO W/O PILOT INPUT THAT WAS CORRECTED 10 MIN LATER, LOST LNAV AND VNAV PLANE WENT INTO CONTROL WHEEL STEERING ROLL AND SPEED, NO LATERAL FLIGHT DIRECTOR WE PUT THE PLANE IN HEADING SELECT BECAUSE LNAV WOULD NOT REENGAGE THEN RESELECTED LNAV AND VNAV AND IT ENGAGED ALL WITH AUTO PILOT ENGAGED. ALSO FMC P/RST LIGHT COMES ON WHEN LOST LNAV. GROUNDED - YES. PER QRH FMC FAILED REF 11.3. ACCOMPLISHED FIM 34-61 TASK 801 FMC BITE LOGGED FMC FAIL LAST FLIGHT LEG, FMC CURRENT STATUS OK, AIRCRAFT OK FOR SERVICE.