The 'dark magic' is going to be your program rebooting every time it gets to that line. I would imagine (this isn't a library I know) that you're exceeding an array bound & generating a 'segfault', although it could be that you light up your LCD array & the power draw causes a reboot.. Because the LED flash is at the start of setup, it executes quickly, so generating the appearance of continual flashing when it re-enters repeatedly. Your code is going to assign g1[0] when the line in question executes - is g1[] defined to point somewhere valid?
