As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEVEL AT 350, ON THE CAPTAINS SIDE WE RECEIVED A VTK FLAG AND THE #1 AUTOPILOT REVERTED TO CWS. AFTER SELECTING HDG SEL, THE FLAG WENT AWAY AGAIN LEVEL 350 WE RECEIVED A VTK FLAG ON THE FO'S SIDE AND HIS DISPLAY SCREENS WENT BLANK FOR APROX 2 SECONDS FLAG WENT AWAY OPS NORMAL. GROUNDED - YES. PERFORMED BOTH FMC COMPUTERS RESET IAW B737-9 AMM 34-61-00 SYSTEM OPTS CHECK OK NO FLAGS DISPLAYED.