I downloaded your source code and took a look. I do not know why -- but your project should not have compiled and it should not have been allowed to be uploaded as is. The last line in your Label class (line 101) has too many Color parameters (3) for a GreenfootImage constructor. You should be getting an error message saying something about 'no suitable constructor found'.

My bad. I was not aware of that new GreenfootImage constructor. The only other possible issue that I see is the two 'if' statements that each could remove the Guy class. If the first one removes the actor, then the second one cannot properly execute (calling 'isTouching' while the actor is not in the world). However, this would not stop the execution after just one act cycle as it appears to be doing here on the site.

I realized you used a 'try-catch' block for the second 'if' which probably solves what I was thinking was an issue. What about the filename at line 56 in the Guy class -- try removing the slash from the: "/ppl2.png" filename.