I see the problem but do not see anything obviously wrong with your galleries.
Also, I notice that if I disable Adobe Flash Player in my browser, the Mobile Player versions of your galleries display fine.
Try re-uploading the 'svcore' folder to your 'plugins/wp-simpleviewer/' directory to ensure that all core files are present and correct (in case a file is somehow corrupt or missing).
Also, please check the permissions on all the plugin's files and folders. Default permissions of 644 for files and 755 for folders should work fine.
You might also like to take this opportunity to upgrade from SimpleViewer-Pro v2.3.1 to the latest version (v2.3.2).
You can download the latest version using the download link from your purchase email. Full instructions can be found here.
Once you have downloaded SimpleViewer-Pro v2.3.2, you can upload the v2.3.2 'svcore' folder to your 'plugins/wp-simpleviewer/' directory.
Hopefully this will help. If not, then try temporarily reverting to a default theme (for example Twenty Fourteen or Twenty Fifteen) to see if this makes a difference. Also, try deactivating all plugins other than WP-SimpleViewer and reactivate them, one-by-one, to see if you can find a conflicting plugin.
I have just double-checked that the current version of WP-SimpleViewer (v184.108.40.206) still works with the latest version of WordPress (v4.1.1 - just released recently) and it seems to be fine in my own test installation.
SimpleViewer Support Team