What is the story where some of the Buddha's followers commit suicide?
What you're looking for is Vesali  sutta.
vesali sutta


  Then the monks — [thinking,] "The Blessed One, with many lines of
  reasoning, has given a talk on the unattractiveness [of the body], has
  spoken in praise of [the perception of] unattractiveness, has spoken
  in praise of the development of [the perception of] unattractiveness"
  — remained committed to the development of [the perception of]
  unattractiveness in many modes &amp; manners. They — ashamed, repelled, &amp;
  disgusted with this body — sought for an assassin. In one day, ten
  monks took the knife. In one day, twenty monks took the knife. In one
  day, thirty monks took the knife.


Edit: I don't think the monks didn't misinterpret the teaching. Perhaps since they're still under training, their mind is not developed and overcome by disgust.