Problem to upload Bootloader

Hello everyone.
I have a big problem with my Arduino board.
I bought a new AVR 168 and I tried to turn up the bootloader and get this error:
avrdude: Expected signature for ATMEGA168 is 1E 94 06
avrdude: verification error, first mismatch at byte 0x0000
0x3f != 0x00
avrdude: verification error; content mismatch

I have a Serial board. I'm sure to choose the right board and the circuit seems fine. I also use XP_stop_polling.
What is the problem???
Please, somebody help me.

Essentially, the hex files that gets downloaded to the board does not match the microcontroller. Could be either the chip or the settings in boards.txt.
(I assume you burn the bootloader using the Arduino IDE.)