I have that same issue on both of my Chromebooks. Certain things will make the flash player crash. If I run the game on facebook I have no issues, but if I do it from the website It crashes. Some of the things that cra* are Opening the friends list, Scrolling on the member list, Opening the mail, Opening the Group Instance thing, and sometimes the ranking page. It started for me awhile back though and it's happened on 2 different Chromebooks. I have no issues with any other browser game either, it's just Naruto Online. It's kind of annoying.