I have had no end of trouble using plotflow and my hp dj 500ps on the mac. The plotter works great as a USB printer, but I have not been able to get it to function using the ethernet connection. I was very excited to see that plotflow X had an option for a usb connection, but whenever I try it, I get an communication error message. Is anyone else having this trouble? It works fine as a USB print in AC and PM. Any advice?