RATIONALE: Erlotinib may stop the growth of tumor cells, and even shrink the tumors in some patients, by blocking some of the enzymes such as epidermal growth factor receptor (EGFR) needed for cell growth and spread. Pemetrexed is a drug that inhibits several key proteins that require folic acid to synthesize DNA. Blocking DNA synthesis in tumor cells has been shown to decrease tumor growth. can block tumor growth in different ways. Giving erlotinib together with pemetrexed at a specific schedule may kill more tumor cells than giving only pemetrexed.