What was found
IN CRUISE, F/O SIDE VTK ILLUMINATED ALONG WITH A/P P/RST LIGHT AND LOST LNAV/VNAV. WENT TO CWS. SINGLE FMC MESSAGE ON SCRATCHPAD. CONDIDTIONS RESOLVED ITSLEF IN LESS THAN ONE MINUTE BEFORE WE COULD TROUBLESHOOT W/ QRH. WAS ABLE TO RE-ENGAGE LNAV/VNAV. ALL OTHER LIGHTS EXTINGUISHED. GROUNDED - YES. PERFORMED B737-9 IFIM 31-65-00-810-A06, NO ACTIVE FAULT WAS FOUND. NO RELATED FAULTS NOTED ON OMS FROM INITIAL WRITE UP. OPS CHECK OF FMC SYSTEMS CHECKS GOOD REF B737-9 AMM 34-61-00.