I like to maximize the tome 4 window to be able to see more of the level, but doing so often causes problem: sometimes the character's graphic changes from a white '@' to a solid white square. Even worse, sometimes *all* enemy and item graphics change to white squares, making the game somewhat difficult to play

The only fix I've found is to restart the game and hope the bug doesn't occur.
Sometimes the game hangs completely, requiring an "End Task" from the task manager to kill it.