Hi,
Based on the error message, and looking at your link, it indicates that process of the page stops during generating the thumbnail for the image of the category "Core Orientator" because it cannot allocate the necessary memory to load the image of that category in the memory due to the memory restriction of your php.ini
As you can see, just for loading that image in memory, it has to allocate arount 71MB of memory, while the total memory use allowed is only 128MB. So that image has a resolution to big. You should reupload this image with a smaller resolution or increase the memory limit of your php.ini and it will then work ok.