OUTLINE: This is a 2-part, multicenter, dose-escalation study of erlotinib. Patients are stratified according to pretreatment (heavily pretreated [received more than 2 prior multiagent myelosuppressive chemotherapy regimens OR received prior craniospinal or pelvic radiotherapy or bone marrow transplantation OR has bone marrow involvement] vs less heavily pretreated).Part 1: