Yep, I got the same thing, on a brand new, fresh install of 1.7.10 with the newest Forge. No other mods. 3.3.7 works fine, though.
Also, bravo on the 16-step collapsible blocks. Thanks to that, I'm pretty sure I now have everything I need for my project.
Edit: Also, apparently I can never post again after this, as my post count has deemed me to be a mathematical dessert. So... good thread for final post?