What is the name of the movie about two children playing with faries and hades in the forrest and their parents called someone kind of a especialis in this matter to find out wha's all about...

Sounds like FairyTale: A True Story (http://en.wikipedia.org/wiki/FairyTale:_A_True_Story),
Or possibly Photographing Fairies (http://www.imdb.com/title/tt0119893/reference).