I've had the chance to get well into a game with Beta 4A and can say that from my perspective it is a VAST improvement over Beta 4 in terms of playability, i.e., the ability to play without the game crashing or freezing up to any degree. The invasion bug and the "unresponsive game" bugs do indeed appear to be fixed. I've not experienced either. That being said, I am still "seeing" the invisible Drengin Super Dominator Corvettes. It's minor and does not affect game play to any great degree but it has been around for a long time.