I've found that alt-tabbing the application, in CO and STO both, completely neuters the action bar when you alt-tab back to the application.

One thing I've found that fixes this, if you're using the Steam download, is to hit shift+tab and enable the steam overlay then hit it again to disable it, then the UI works again.

I am unsure why this occurs. Previous to using the Steam overlay to jumpstart the game UI again, in CO and STO both I literally had to restart the client.

Accessing the bug interface may have been what did it for you, but it seems to be a universal bug in their XUI scripting.