Dragon's Dogma's Arisen meet all kinds of horrible deaths pretty much all of the time, but a save-erasing glitch isn't nearly as fun being rent in twain by an angry griffin.
A recent patch for the original game and expansion Dark Arisen has corrupted some players' saves, making hours of progress through the tough open-world RPG go up in smoke. Capcom advises all players to backup their save files to an external storage device before playing, particularly for players who are resuming after a long break.
Capcom says it's investigating the issue and hopes to have a solution soon. If you haven't installed any title updates recently, you may want to play offline just to be safe.