Avatars sometimes don't show up or not totally. That's a sign the theme needs updating.
That sounds like a internet connection issue indeed. Usually when you load in a website, the image files are the last to be loaded and therefore the slowest and in cases where the connection just flat out fails, it is the first thing you'll see fail. Avatars being an image file, where as the theme isn't.It might just be the internet connection, but updating does make avatars show up (for various forums) on my satellite connection.