I've started new games and each one replicates the error no matter what tech choices I make or starting conditions I select. Guess I'll go play Master of Orion for a bit, then.
I'm having the same problem. I found out I was fortunate enough to share a border with the Krynn. In anticipation, I started to build my military along their border. That upset them so they attacked. They took some of my outer worlds so I attacked their core systems in retaliation. And I got this error... They have no problem taking my planets, but I can't conquer theirs. I am no in the beta, verifying the game cache did nothing, and reloading/restarting did nothing.<br