As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT CRUISE 34,000 ENCOUNTERED A DUAL FMC FAILURE. VTK ILLUMINATED ON BOTH ND'S AND BOTH FMC'S BLANKED. DUAL OPERATION RESTORED BY ITSELF IN APPROX ONE MINUTE. GROUNDED - YES. PERFORMED FLIGHT MANAGEMENT COMPUTER SYSTEM BITE PROCEDURE REF B737-800 FIM 34-61 TASK 801. DETERMINED FAULT INTERMITTENT AND BOTH FMC'S NOW OPERATE NORMAL. OK FOR SERVICE.