Just tried Dungeon Siege in 11.1 then in 11.2. Both show the same behaviour; distorted in default full-screen, but switching to windowed via Restore Display (Alt-Command-R on Mac) makes the game run fine... Until you load a game, start a new game or quit from a game to the main menu, that is. This causes the game to go back to full-screen mode, which brings back the the distorted and unusable view seen at the start.
Also, when I say "fine", I mean the frame rate is a bit poor (not as good as Dungeon Siege 2 in the same version of CrossOver), but otherwise has no graphical abnormalities.