The combination of chemotherapy [such as docetaxel] with continuous administration of targeted drugs which block the molecular machinery of cancer cell growth [such as erlotinib] have failed to improve their efficacy over only-chemotherapy in patients with metastatic lung cancer of the non-small cell histology type. It is not yet known whether administering targeted drugs intermittently could result in improved efficacy of the combinations. This is a multicenter randomized Phase II trial aiming to determine the more active dosing sequence between intermittent erlotinib and docetaxel for treating patients with advanced Non-Small-Lung-Cancer.Patients will be randomly assigned to one of two treatment arms: they will receive a 12-days course of erlotinib either before docetaxel [arm A] or after docetaxel administration [arm B].Treatment will be repeated every 21 days.Patients will be evaluated every 2 cycles (~6 weeks) for response using RECIST criteria. Those patients achieving stable disease or better will continue therapy up to a total 8 cycles. Those patients experiencing progressive disease will be taken off study. Biopsy material will be assessed for biomarkers.