I installed the game in with beta4, and it was running perfectly.
Then I updated to beta7, and the game still runs very well. The only problem is that the character faces in their portraits at the top left of the screen are completely black. The same is true for their faces in the Inventory screen. The in-game faces are fine.
Could the update have changed some configuration in my bottle? Should I create a brand new bottle and see how it works there?