Give evidence from text that Montresor in unreliable in "The Cask of Amontillado."

In "The Cask of Amontillado," Montresor is an unreliable narrator.  At the beginning of the story, he tells the reader that he has had to bear "a thousand injuries" from Fortunato.  However, Montresor never goes on to qualify exactly what Fortunato has done to him to cause him to want to take such harsh revenge.  When the reader encounters Fortunato, he appears as a bit of a braggart, but nothing more.  Yet Montresor insists that Fortunato deserves the punishment that is coming to him.  As Montresor leads Fortunato further into the cellar, the reader gets the sense that some ill fate is about to befall Fortunato from the hands of Montresor.  And indeed, Montresor walls Fortunato up in the cellar, all the while claiming that Fortunato is at fault.  Such evidence suggests that Montresor is not a reliable narrator.