As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GOT VTK AMBER WARNING FLAG ON CAPT'S ND, BOTH CDU'S LOST FMC AND MODE LOST LNAV AND VNAV, DURING CRUISE FOR 15 SECONDS ( AUTOPILOT WAS IN CMD A ). EVERYTHING RECOVERED AFTER 15 SECONDS AND OPERATED NORMALLY AFTER THAT. ACTUALLY, IT HAPPENED AGAIN SEVERAL MORE TIMES. GROUNDED - YES. ACCOMPLISHED LEFT FMC RESET PER B737-900 FIM 34-61 TASK 836 FMC RESTORED. OK FOR SERVICE.