I've been running 13.04 for about a month now without any kind of issues. I have a dedicated laptop (running windows xp) connected to my ultimaker solely for the purpose of printing. There is literally nothing else going on in the background. It is a fairly powerful machine, I have no doubt it is up to the task.
I upgraded to 13.06.4 today and tried my first print on it, only to have it fail about 2 hours in. It simply stops mid-print, the hot-end remains heated and continues to happily melt the stuff it is contact with.
I switched to the term tab and noticed a ton of these same strange checksum errors that you are seeing. So I loaded my model back into 13.04, sliced it, and it printed flawlessly. I checked the term tab to see what was going on, and there was only 1 instance of the checksum error right at the beginning of the print.
I've started another print to see how it ends up, and it is already throwing hundreds of these checksum errors (but so far continues to print).
I don't think it is a computer related thing, because it only became an issue when I upgraded Cura.