Are the images set as default class images or actually being referenced in code? if in code, show how they are being referenced (show the class code in which a reference to one of the images is being made).

Thanks Dan! I am new to Greenfoot this year. It appears they are images the students are selecting when they create a new subclass. These are images they created and put in the images folder. So I think that means we are talking about "images set as default class images" and are not actually referenced in code.

Does everything compile fine (are the 'Run' and 'Reset' buttons active)?

Their game opens and seems to load, the run button is green, but everything is frozen. It does seem to be the case that for the students affected, they have a large number of initial objects.

Try having the number of object reduced. Also, try to have them limit the size of the world to something like (900, 600), at most. I cannot think of anything more to suggest.