Interesting, the Arduino Duemilanove or Nano w/ ATmega328 bootloader works like a champ!
So maybe not a bad chip.
Maybe the Optiboot loader should only be used with the Uno (because of the ATmega8U2 interface)?
Maybe timing is different?
I've used the Optiboot successfully in several non-Uno instances, but maybe I've just been lucky up until now.
I suspect it's too late now but when you tried using the processor with the Uno / Optiboot bootloader did you remember to select Arduino Uno?
It's good to know the life of an AVR processor has been spared!
Auto-reset not working as it should?