I just logged in the backend of your site and enable Error reporting and see that the problem comes from the limited PHP memory size. Please try my suggestion below:
– If you have access to your PHP.ini file, try to change memory limit from 32M to 64M: memory_limit = 64M; Maximum amount of memory a script may use up: 64MB, so setting it with 64M is recommended. Depending on your need, server condition and your site, you could use 32M, 96M, 128M, 256M, 512M, 1024M, 2048M, 4096M. Make sure your server allows you to register that much dedicated memory.
– If you don’t have access to PHP.ini try adding this to an .htaccess file: php_value memory_limit 64M
As this relates to server side, it’s best if you talk to your hosting provider for further assistance on this.