Geeetech

I don't think the wires are the problem because the printer works fine for a moment, exept it can't communicate with the computer. Then the blocks start to appear. I am trying to re-upload the firmware but I am not shore that it is the problem. Thank you for your help

When I boot up my prusa i3 pro b it works fine for about 3-5 seconds but after that the lcd gets unresponsive, show lines of black blocks and the sanguinololu stops following commands. What shall I do!? help me!