This is a kids' movie about kids; what I can remember from this pretty old movie is vague.
A boy reads a book, in that book is a scene where a man or a boy is riding a horse to a fountain. They try to drink from it but it affects them, freezing the two. The boy who reads this book tries to skip a few pages or all of them to find out what happens to those two characters in the end, but all the pages are blank.
This movie may or may not contain (this may be another movie) some kids flying inside a wooden ... dragon?
From what I can remember, it is around 20 years old. It's not "The NeverEnding Story", even though my story is similar. It may be a TV series.