Docetaxel in Combination With Zactima (ZD6474) in Patients With Locally Advanced Squamous Cell Carcinoma of the the Head and Neck

* Participants will be "randomized" into one of the following study groups: Docetaxel or Docetaxel with Zactima. Randomization means that participants will be put into a group by chance. * The Docetaxel group will receive docetaxel on the first day of every treatment cycle, which lasts for 3 weeks. Even though treatment will occur once every three weeks, participants will return to the clinic on a weekly basis for the first two cycles. After the first two cycles, they will only have to return to the clinic at the start of each cycle. * The combination Docetaxel and Zactima group will also receive docetaxel once every three weeks. In addition to the docetaxel, they will also take a Zactima pill orally every morning. They will also have to return to the clinic on a weekly basis just as those in the docetaxel only group. * The following tests and procedures will be performed during each cycle of treatment, regardless of which group the participant is randomized into. These are considered standard of care for treating patients with chemotherapy for recurrent head and neck cancer: physical exams; blood tests; urine test; nasopharyngoscopy; repeat imaging of the tumor (x-ray, CT, MRI or PET); photographs of the tumor. In addition to the tests mentioned above, the Zactima group will have EKGs performed 3 times on the first day of treatment, once at week 2, then at the beginning of cycles 2 and 3, and then every 6 weeks. * Participants will continue on the study as long as they are receiving benefit and are not experiencing any unmanageable side effects.