Thx for the answer, I also posted your answer in the thread I created in the forum.
Still, there's something the screenshot isn't telling. The Thread at the top-right is the incoming wave of the AI Core Raid Engine (From what I've read if I mouse "mouse-over" the "Threat" in the HUD). And if you want, I can send you my game and you'll indeed see that after the countdown, the Purple AI (left side) indeed send a "carrier only" wave of about 4500 ship, but right after I killed it (I'm not sure if killing the wave is what triggered it, but it's how it happened) the yellow AI (right side) send me another "carrier only" wave of around 4000 ship and again, after I killed it the Purple AI send another "carrier only" wave of around 4000 ship. For a total of more then 10 000 ship 
.
Here's the link of my save in the case you would like to see it yourself : http://www.mediafire.com/?v09zhr2cqks8088
Moving this out of PM...
I think what is being misunderstood here is what "threat" means. Threat is ships that are already in the galaxy, from past waves or ships retreating, etc. Having a threat of 3.4k has nothing to do with the current CPA, it's just existing ships that you've failed to kill in prior encounters (or which have yet to come forth and engage you because they are stalking you from nearby).
With CPAs or waves that have
not yet arrived, that's the "wave" countdown. Even though the CPA ships are technically in the galaxy, they show up under wave instead of under threat because which ships will become threat doesn't get determined until the countdown timer hits 0.
In terms of the carriers, that's just the AI moving some of its ships into those because it has excessive extra ships on one planet and that would become a CPU burden otherwise. Most likely it's hitting the point of several thousand ships about to swarm into your planet at once, so it puts them into carriers to save your CPU and keep the game speed up while it trashes you.
In terms of those carriers that keep hitting you for more than 10k total, that could be any number of things but it doesn't strike me as odd. For one thing, about 8k of those are already accounted for, so it's just a difference of maybe 2k max. There are various mechanisms that lead to carriers getting created and coming after you, most to do with too many reinforcements stacking up on AI planets that already have a barracks. Given that most carriers include 1k ships, that's only about two planets at once happening to trigger.
In general, this particular scenario is in a floodwater sort of state: you've really, really,
really angered the AI, beyond what most players can survive, but you haven't died yet and so the AI is still hammering you like crazy. Given that somehow you're still alive, I'd say you might have a good chance to actually beat them if you can survive this rough period. Those large CPAs only happen every 3-5 hours, and that was a huge amount of your threat. Then there's the other mass of threat (3.5k) that it sounds like you killed. And then the carriers that would have launched at you anyhow, based on their planets filling up, and now those guys are dead.
So it's not like the AI will keep doing this indefinitely on this scale, but you caught a really bad confluence of events there; if you survived, then
very good job, that's impressive.
