Passiert das Gleichen mit einer anderen Software? Probier mal Putty oder TeraTerm.Corrupted Config Files
Saved configurations can be corrupted in odd ways. The most obvious symptom is that typing the same character three times in a row causes the third instance of the character to be sent incorrectly. In other cases, the terminal program fails to work altogether. The only fix we know of is to create a new configuration from scratch, as described above.