My only other suggestion would be to pull the avrdude from an older Arduino install for 64-bit, and try that. If that doesn't work, I could try to send you a copy of my avrdude (I only have 0019 setup, currently, though)...
My only other suggestion would be to pull the avrdude from an older Arduino install for 64-bit, and try that. If that doesn't work, I could try to send you a copy of my avrdude (I only have 0019 setup, currently, though)...