This is a phase II study of Nilotinib for patients with advanced GIST that cannot be surgically removed. Patients are candidates for the study if their tumors have progressed on imatinib and sunitinib or if they were intolerant to these drugs. Patients may have received other investigational therapies as well. We are testing the benefit of nilotinib in advanced GIST looking at the length of time disease is controlled as well as the response of the disease to the drug.