Hi RunningWolf.
Since your Rx is flashing, I suspect your bootloader on the Atmega328 got stuck somehow. Try this out:
If you hook up your Diecimila as the programmer (and upload the sketch) and the Uno SMD as the "board to be programmed", this sketch will let you open a serial monitor @115200 baud on the Diecimila and you can reprogram the bootloader.