So... many of you are missing the point of this thread... I think. Unless, I'm mistaken, the thread is about films that were adapted from another source material, that works well for that material, but not as a film. I didn't think this was a thread about complaining about what movies you hate, but what ones from another medium don't work as a movie.
This is hard for me however, because some movie adaptions are not bad because the material couldn't have worked for a movie, but because the filmmaker screwed up teh material and just made a bad movie.
The Last Airbender is a great example. From the animated series, it works great, and I believe if handled right, could have worked for live action, but M Night is an idiot.
Let me try and think of one that just does not work as a film... It's hard because I don't see movies that look like they will suck... OK... even though I'm not a huge fan of Dragonball... I think that is a great example of something that does not work for a film structure.
Oh, and Super Mario Bros... would never work for a film. That may be the best example.