Did you attack other civs that they had contact with too? (The AI doesn't know how to make friends yet though, so that's not a reaction to attacking a friendly civ. I was about to code terraforming of minor race systems by the AI to help with that, BTW.)
So, let me try to recap. You're probably playing the Feds. You're allied (as in, have an Alliance treaty) with the Cards, Dom and Klings. The Klingons have zero Regard towards you, and DoW on you. You propose a Cease-Fire, they accept, and some time later they DoW again. Is this correct? I need to know the full context in order to understand the situation.
BTW, the last part is "intended", in that Cease-Fires only last for 25 turns - to give you a chance to improve relations. When the CF ends, Regard will go back to the previous value (modified by whatever you did in those 25 turns).
As for zero Regard with an allied civ, that's not intended... that treaty should have been cancelled.
And I need to find out what made their Regard towards an ally drop so drastically.
Ok, thanks. I've since overhauled the food production code. It's not perfect yet, but should be better.I oversaved that game, but their pop was decreasing to some lvl, then increased and then decreased again, like there isn't enough farms for growth, but if I encounter this again I will send save to you.