We will have to look into it on Wednesday when you can share your screen in Wimba. My best guess is that you need to use the right saving format - i.e. save it as the ggb file and not, say, as a picture. If you run Snow Leopard on Mac, there used to be some Java errors (the forum says) but they should have been fixed by now. Here is the thread:
http://www.geogebra.org/forum/viewtopic.php?f=8&t=7817
Cheers,
Maria Droujkova
Make math your own, to make your own math.