In the system operating(in my case Windows 7 x64) if i change the windows from Repetier-host and resources explorer (for example) or any folder or program, the printer will block the movements for a fraction of second. If i do this change very fast and many times, the printer almost stop!
The firmware is marlin.
My Windows has something; any idea?
Non ti fidi 
Or get yourself a Raspberry Pi, and run @OctoPrint . Nice and low cost, frees up your PC to do other things.
The problems with SD cards is that the socket wasn’t really designed for high volumes of insertion/removal, unlike USB. OctoPrint will let you queue jobs, monitor remotely, etc.
@Mauro_Manco mi fido è solo che trovo pareri discordanti e comunque nel mio caso mi sarebbe molto più comodo avere sempre il pc di fianco per poter tener sotto controllo la stampa.
@Mark_Rehorst The reprapdiscount full graphic smart controller find the sd card but not find the file. I can’t use repetier or pronterface for copy the gcode becouse are too slow, but there is some tricks for do that via pc? Sd format type, file extension? filename sintax?