Are you by any chance utilizing the VPN service in Opera when you use that?
No, no. I always connect in "raw"; without proxys or other... What I was actually saying is that the only way DirectAdmin is 100% fully functional is by using a Chrome browser. I can login with the Pale Moon (currently, v28.8.2 x64), but some features doesn't fully work. In example, the «My Messages» feature. I can see the subjects in the list, but when I click on one of them, nothing happens. With a Chrome browser, I'm able to read the messages.
Or, another example, the «MySQL Management». The "+" buttons in the databases list does nothing with Pale Moon, but they work with a Chrome browser.
Anyway, it's not fault of anybody of you, as this is happening too in the demo of the official DirectAdmin website.