You don’t mention it explicitly, but did you flash the controller board using the Arduino IDE? I don’t believe the controller cards are pre-programmed at the factory. Also be sure that you are not using the latest Arduino IDE, as there are compatibility problems with the latest libraries. You want to be using Arduino IDE 1.0.6.
This sounds like a communication problem over the serial port. Make sure you have set the BAUD Rate in the computer settings for COM4 to match what the printer is using. By default, the K8200 uses 250000 BAUD.
I had difficulty using 250000 BAUD on my Mac. I ended up changing the rate down to 125000 both in the firmware (see Configuration.h) and also in the Mac serial port settings. This makes for slower communications, but that is not the limiting factor in 3D printing speeds.
I hope this helps.