I've heard of this. This is known in the game industry as the "unbeatable boss". Forums reported it is beatable but it takes 18 hrs. Actually, after 18 hrs, they still didn't beat it. The original came out in 2003. The expansion pack came out in 2007.
These folks wasted 18+ hours all because a setting in a config file told the boss to be that hard. When that's on my mind, I'd stop the game.

http://www.g4tv.com/thefeed/blog/post/688158/Final_Fantasy_XI_18_Hour_Boss_Fight.html


BTW:
I played a handful of games and multi-user dungeon (MUDs, basically a role playing game) throughout the night and through the next afternoon before. It was addictive especially if you're progressing. I'd think about the game all week until I get to an impassible point or if it becomes repetitious. I never played against one boss for that long. My record may have been throughout a night but that's it.

On a couple of occasions, my character would get deleted by either the admin or if the cartridge gets broken. All the hours and wasted summer days. For nothing. Then I realized a video game something a code writer put together, tested it (maybe) and released it. After a few years, the game becomes completely forgotten. Able to get really far in Phantasy Star? Who cares. They stopped making a Sega Master System almost 2 decades ago. Time you can't get back.

I understand wanting to know what the last scene of a game looks like but its just that. A scene whipped together by a bunch of dudes.