You waste a lot of RAM with holding all these strings in the main memory. Learn to use the F() macro.
Please post a complete wiring diagram and detailed information about how you power the system. I guess you have a power problem, the voltage probably drops and the brown out detector resets the unit.
I doubt that this code produced the posted output. You check some time variable but you don't update them in the main loop. With this code the time would be printed once and never again until the Nano reboots for whatever (probably hardware) reason. Post the actual code!