It's a bug in the site, I hope the owners can have it fixed.
Long story short: the link to the source image for non-advantage users has not been set up correctly on these 'broken' contests.
Long story:
The code to set up contests is very old and runs by itself. When new sources are voted in, the image with most votes gets assigned to the next available contest (about 6 months in advance) and generates a few sizes with random file names for each image, e.g. for the 'Blue Piggy Bank' contest there are
A thumbnail
https://photoshopcontest.com/images/queue/thumbs/3664538379f4f0844c2babc628ec807f1a67abf399491.jpg
A full size source (1280 x 960 pixels) for advantage users
https://photoshopcontest.com/images/queue/fullsize/29059379f4f0844c2babc628ec807f1a67abf364770269.jpg
A reduced size source (800 x 600 pixels) for non-advantage users
https://photoshopcontest.com/images/queue/large/3664538379f4f0844c2babc628ec807f1a67abf399491.jpg
An odd size (475 x 356 pixels) that is shown if you click on the source thumbnail from an entry page, not from the contest page
https://photoshopcontest.com/original/display.html?image=/images/queue/3664538379f4f0844c2babc628ec807f1a67abf399491.jpg
When we fail to feed the source queue for a long time, we end up with days where there is no new source to assign to the next future contest. The old code doesn't account for this and we end up with 'broken' contests that don't have a source or a title. The only workaround so far has been to email the owners a new source image, and they edit the code for the broken contests to point to these manually added sources.
From what I can see, there have been a few patched broken contests recently - Scooter, Sharp Rocks, Shattered Glass, Shiny Thumb.
For the Scooter Contest there are
An oversized (475 x 356 pixels) thumbnail
https://photoshopcontest.com/images/queue/thumbs/Scooter-thumb.jpg
A full size source (1280 x 960 pixels) for advantage users
https://photoshopcontest.com/images/queue/fullsize/Scooter-large.jpg
A broken link for non-advantage users
https://photoshopcontest.com/images/queue/large/Scooter-thumb.jpg
There is no image saved at this address, so PSC defaults to the error message page. If set up correctly, the link should have been pointing to an 800x600 version of the source image.
Solution:
Option 1 - try manually entering the address .../queue/fullsize/[Contest Name]-large.jpg
Option 2 - use reverse image search to find the original on the Interwebs, 99% of the source images come from libraries of free stock images.
Warning:
There are A LOT of broken contest coming up in a few months, for which even the workaround images have not been set up. I emailed rajan (the owner) a lot of sources to fill in the gaps, but I haven't heard back.
