Go to
http://www.nbc.com/Heroes/novels/index.shtml?novel=30
And the comic book basically says just what I did. Future Hiro tried to kill Syler but he couldn't because Syler had killed Claire.
So he went back and warned Peter...but when he went back nothing had changed, and past Hiro was up in the loft...
So again, my only question is in Timeline 2 (where Peter did save the Chearleader), why is Syler still alive? Obviously the bomb went off because it was Peter exploding (something Hiro did not know), but if Syler did not have regeneration capabilities, how does he live when Hiro stabs him? Somehow that didn't happen in Timeline 2. But Hiro goes back to Timeline 3 to make sure it does.