Reporting this to both mods, because I have no idea which caused it. The odd bit is the world I was trying to join has absolutely nothing from either mod anywhere near me yet.

http://hastebin.com/pexinozexe.vhdl

dmillerw/RemoteIO#76

I have no idea why, but removing the Wallpaper mod fixed it. http://minecraft.curseforge.com/projects/wallpaper