Using nRF24L01+

No, in RF24.cpp is the following function, and I patched the last line as shown,

void RF24::begin(void)
{
  ....
  if( setDataRate( RF24_250KBPS ) )
  {
    p_variant = true ;
  }
  // Then set the data rate to the slowest (and most reliable) speed supported by all
  // hardware.

// MODIFIED - 02/26/13.
//  setDataRate( RF24_1MBPS ) ;
  setDataRate( RF24_250KBPS );
  ....
}

Don't ask me what the comment means, I don't know.