avr signature doesn't match, flash address 0x0000 wrong
Most likely you are running the programmer at too high of a bit rate. The bitrate can be set on the command line with the -B N flag, where N is the period of the programmer SCK signal in microseconds. Try something high like -B 100 and see if you get more consistent results. The following link seems to show how you would set this up in AVR Studio (v4): Atmel STK500 Programming.