Thanks for the quick reply. I originally thought that this was a software issue of some sort due to the ‘IndexError’. However, I found that this occurs anytime plotting is in progress and I unplug the USB cable. I do this since the cancel button does not work. I was able to print my stipple file on a Windows XP machine (yes, I still have one), so the file must be ok. After reading the link you supplied about the hardware problem, I setup the Egg Bot back on my MAC, but did not use the USB extension that I did on my previous setup. This time it worked fine and would plot the entire stipple.svg file. Cool!!