I had this problem also, and I tried all of the firewall suggestions, still wouldn't transmit. Here's how I got it to work:
1) I lowered the firewall as suggested in other posts.
2) Instead of trying to efile the federal and states at the same time, I efiled each return individually. So I started with federal and then each state. Each of those returns individually went through on the first try without a hitch.
I hope this will help someone.
