This happened to my best friend last night and pointed me to this link when he did some research. Just passing it along.
Originally posted by ArticleUnfortunately, gamers eager to sample the cel-shaded beat-'em-up were in for a very nasty surprise. That's because the demo contained a glitch that will erase all saved games on the memory card or cards currently inserted in the console.
07/03: Ninja Gaiden Sigma - getting good reviews. Days till Madden: 43. Though more relevantly, it's two weeks till NCAA and All Pro 2K come out. No games next week, maybe The Bigs will show up so I can play it and complain about it.