Yep, sounds like the people in that thread are having the same basic issue I'm having. I found that if I go to windowed mode it starts working and then I can go back to full but it just clones the aquarium on all three displays rather than spanning them all. From the looks of it no real solution has been found yet?
I hope this issue will be resolved soon because I love 3.0, it looks much better than 2.6 and that's saying a lot because 2.6 looked amazing.