In this study, the investigational drug, temsirolimus, will be combined with cetuximab, a biologic agent used in the treatment of colorectal cancer. Cetuximab in combination with temsirolimus may be more effective in treating advanced colorectal cancer than cetuximab alone. The purpose of this research study is to try to define the highest dose of cetuximab that can be used safely in combination with temsirolimus to treat advanced colorectal cancer that has progressed through standard therapy.