avrdude: verification error; content mismatch

Hi guys, i bought an Arduino 2009 a few days ago, and everything (including sketch upload) worked fine until i tried to power it with the +12v DC line i got on my car: the board seemed to work properly the first 10 secs, then the leds (i got 10 connected from pin 2 to pin 11) started blinking and working like the board was running the sketch i uploaded the last time (and i think it was overwrited by the current one). Now i can't upload any sketch and the only outputs the board gives are the power led, the led13 one-blinking after reset and the tx/rx blinking when uploading, but i always got this error: (link in the second post because i can't link in my first message) My suspects are: 1. I accidentally shorted the +12v and the signal (connected to the analog 0 input) wires, so i fried something on the board/chip; 2. I uploaded the first sketch under windows, and the second under debian, so I corrupted the bootloader for somewhat reason (i notice you that now i got the same error output both in windows and linux).

Got any ideas? Thanks in advance from the arduino's country. ;)

Here's the output: http://pastebin.ca/1803689