A weird thing, however, is that after 45 seconds or so it does play again the sample! And keeps doing so every after... :?:

Click to expand...

Some uninitialized part of the hardware is acting as a "watchdog timer" and triggering a reset after roughly 45 seconds? (So you're basically just rebooting over and over again, but since the picture-drawing loop is just stuffing the same data into the video buffer over and over again you're not seeing any visual indication?)