Gastroesophageal Reflux Disease (GERD) is a common disorder caused by the reflux of gastric (stomach) acid into the esophagus. The exposure of the lining of the esophagus to the acid will cause damage to the esophagus over time. The symptoms of GERD include heartburn and acid regurgitation This study will determine if Tegaserod alone and in combination with omeprazole is safe and relieves the symptoms of heartburn.