PaulS:
If you are sending nothing to the serial port, the while loop has no affect, so your program is equivalent to:void setup (){
Serial.begin(9600);
}
void loop ()
{
Serial.print("print");
}
Which should make it pretty obvious why it keeps printing "print" over and over.
Do you maybe know, what should i do program to stop after print() and wait for some incoming byte from serial monitor and then go on?