One has just worked for me. Not that it was one I wanted to upload, but I needed one to test it with.
Might depend which browser you are using. And what updates that browser has had lately. I had one site where Flash was required for the photo uploader to work, and that worked okay with Chrome but not Firefox one day. It turned out the newest version of Flash didn't get on too well with Firefox. To fix that I had to uninstall v.11 of Flash and then re-install Flash 10.3.
Hope that possibly supplies a clue. Of course looking at the time, it might be better to just say screw it for tonight, it might all be better in the morning.