So I've install wp-photocontest 1.5.6 and everything seems to be OK when I was using Firefox.
Except an error message in the header:"Warning: Cannot modify header information - headers already sent by (output started at /home/.../wp-content/plugins/wp-photocontest/view.php:1) in /home/.../wp-content/plugins/buddypress-group-documents/index.php on line 271"
But this message error doesn't restrict any action with Firefox.
As soon as I tried with Explorer, Safari, Chrome, no pictures show anywhere. Just an empty polaroid frame and a"No page found" when I clic on it.