Hi! What kind of package you are using? INT0 isn't pin 11 (DIL40-TxD, LCC-RxD, PQFP-T1) or maybe I understand you wrong.
Why you put pull-up resistor at pin 31? If it is dil40 package (EA/VPP), it have to be held low to enable the device to fetch code from external memory!!! In LCC package it is pin 35, in PQFP - 29.
Write about the signals, not pin numbers. Good luck!