GREEN VEGETABLES AREN'T ALWAYS GOOD FOR YOU <P>The new restaurant in town is a hit, but when several diners get sick, the Health Department threatens to shut the place down. And if the restaurant closes, Todd and Noelle's new friend, JoAnn, may have to move. <P>Mr. Merlin's Third-Grade Detectives want to prove that the problem wasn't the restaurant's fault. But Mr. Merlin's clue doesn't make any sense -- how can green be dangerous?