be·dev·il
 /bıˈdɛvəl/  verb  , -ils,  US   -iled  or Brit   -illed,  US   -il·ing  or Brit   -il·ling [  + obj  ]
  : to trouble (someone or something) in a constant or repeated way : to cause repeated problems for (someone or something)
   The theory bedevils scientists, none of whom have been able to prove it true or false.
   The project has been bedeviled by problems since its inception.