Are you alluding to this?
but when I open the serial print all I see is:
I believe it is caused by inadequate power.
I had this just a couple of days ago, and all I had done was change the motherboard in the desktop. Getting power from a 9v wall art solved the problem. This is not as inspired as it might sound, there had been signals before about sailing too close to the edge, and I was fortunate in that both my code and proto shield had been proven 100% kosher. An LCD display, or firing up the Ethernet or more likely to be the villain. I see no evidence of that here, but it could be just a bit of slack arsed soldering, which would lead to the same result.
If what I say sounds right but you have no external PS, you might be able to fix it by running off a USB at the back of your box. I was using a non-powered hub in the front.