What do you mean "when entering any of the default gallery"? As far as I can see, you only have the default galleries. When I click a thumb, I see this, as is normal:
Try this: Go to panel->settings->settings, disable X3 CDN. Perhaps your network is having problems, and some of the resources are not being loaded ...
If not, I don't know what to say ... It's definitely working, but if anyone else can click the link and test, please do. If there was an error with server/gallery, nobody would see the images.