RATIONALE: Drugs used in chemotherapy, such as gemcitabine hydrochloride and oxaliplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Erlotinib hydrochloride may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Giving gemcitabine hydrochloride and oxaliplatin together with erlotinib hydrochloride may kill more tumor cells.