Phase I trial to study the effectiveness of combining erlotinib hydrochloride with irinotecan hydrochloride in treating patients who have advanced solid tumors. Erlotinib hydrochloride may stop the growth of tumor cells by blocking the enzymes necessary for tumor cell growth. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining erlotinib hydrochloride and chemotherapy may kill more tumor cells.