How about this then:
SoftwareSerial LCD(0, txPin);
You are using Pin0, which is part of the hardware UART, and pin 4 which is not - think you should use something beside 0,1 for software serial.
How about this then:
SoftwareSerial LCD(0, txPin);
You are using Pin0, which is part of the hardware UART, and pin 4 which is not - think you should use something beside 0,1 for software serial.