Hi Ben,
At work at the moment, I just tested it and it uploaded without issues for me
I'm not sure what to suggest. You've uploaded before fine so I guess your not trying to upload photos that are of an enormous resolution on a slow net connection? Your files are in a .jpg format as well I guess?
If you want e-mail me the photos and I will upload them as you for now and we can try to resolve this later.
Cheers