The normal Arduino oscillator frequency is 16Mhz and the data sheet suggests an error of either 2.1% or -0.8% at 57600 baud.
Are you running an Atmega 328 at 1.84.... MHz? Does the Arduino IDE know that that is what you are doing?
I have never had any problem communicating with my laptop at different baud rates using 16MHz and 8MHz Atmega 328s.
...R