you have to compile letter bomb for each console using the correct mac address and wii region, are you sure you didnt try to use the same one on the other console ?
better double check cos as far as I know letterbomb has never failed or froze
You might want to try the new exploit called "wilbrand". It can be created through a PC app called ModMii.Which system menu do you have? It has to be 4.3.
4.3e