What you need to do is the following:1. Go back into the Beet Hoven, save your game, and then quit the game.
2. Find the location of the game files, and in the folder called "minisaves" use Windows Explorer to delete all the files in there that start with "sturmfordcity"
3. Load the game again, restore your position, and continue playing. You should find that now everything works.
What you have done is to force Sturmford City to respawn, and this generates a fresh non-corrupt location. (As a bonus, you will even find that the two shamrocks that give skill point bonuses have regenerated. 
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All sorts of things can happen in this game, and in my experience, what happened to your game usually occurs at least once. Another time you may need to do this is when one of the teachers mysteriously vanishes.
