Are any of the AIs at war with each other? And what are your current relation levels with the ones that won't trade with you?
Sorry it took so long to get back on here - no, there are no wars at the moment, and the relations are as following:
Arcean Empire - Cool
Terran Alliance - Cool
Iconian Refuge - Cool
Drath Legion - Wary
Lentzlandians - Neutral
Dark Yor - Neutral
Snathi - Neutral
Caranoids - Neutral
I had filled up my allotment of trade routes, but i don't remember who all they were with - only 1 (at the most) was with the Drath Legion. I still have one left with the Caranoids, but that's it. Now if I send a freighter to any of them, it just gets to their planet and stops outside of it. My ships also cannot go as far as they had been into the galaxy, but i did not lose any planets or starbases.
i kept the save from this point, but the game is now in all out war b/c i got fed up with the Lentzlandians building 4 influence starbases right around my home planet and soon after i formed an alliance with the Arcean (developed 1 trade route with them, but the other planets would not take the freighters)they got attacked, which made me at war as well, and now it's an all out brawl.
thanks for the feedback thus far, and if anyone knows how to avoid this in the future, please do tell! i was up to -200 bc / turn, but have subsided it to -50ish by cutting spending to 60%, raising taxes to 45%, and building stock markets.
edit: i made a custom class (the Maruukoi

) with an Economics bonus of +20%, Diplomacy +10%, and Trade +10% - don't know if that would really matter at this point in the game...