The purpose of this study is to determine the safety of SU011248 and the highest dose of this drug that can be given safely in combination with the chemotherapy drugs irinotecan and cetuximab. Laboratory studies have shown that SU011248 may block the growth of blood vessels in tumors, which may prevent tumors from growing any further. Other studies have demonstrated the possibility that SU011248 may enhance the anti-tumor activity of other chemotherapy drugs such as irinotecan and cetuximab.