Avatar cannot be changed in Social Theme

Hi there, I have installed the Social theme and have not been able to upload a new avatar. It will allow me to browse and upload, but then there is no image once it's uploaded. It has a "crop" button as if the image is there, but there is no image to crop. If I click to crop it, the image still doesn't crop.

Please advise, I am not using a plugin. I'm using just a single install of WP.

Thanks!
Clare
modernsingleparents.net