My tablet has Android 4.4 and the latest beta version of Opera but this has been happening for several versions now.
What happens is that randomly when i start keying in the addressbar Opera locks up completely and has to be killed to restart it.
I smply click on the address bar google keyboard comes up.
I start typing and after a random amount of keypresses it locks up.
It doesn't happen all the time either. It's random and it can happen when im meeting keywords for a search of a website.