As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE TRYING TO SELECT DIRECT TO A WAYPOINT ON THE LEGS PAGE AT THE F/OS CDU BOTH FMCS LOCKED UP WITH STANDBY ONE DISPLAYED. ON OTHER MESSAGES, BOTH FMC COMPUTES LOADED CORRECT SOFTWARE AND NAV DATABASE. ALL CHECKED NORMAL PER AMM 34-61-01. THE AIRCRAFT WAS GROUNDED.