I have provided a link to the world as a media fire link for Dinnerbones again. I helped once with the beacon bug last time. This bug is with signs now. If you go far from the source, the text will vanish from the signs. The only way to fix it is to log out, but that can be annoying to do every time you go far from the sign location.
I tried to look at previous bugs, and I don't see anyone reporting this one. I have pictures and the world. If you want me to give more information, let me know before 1.4.7 comes out officially.
World from start to finish, all you will need:
MC-3564 Debug message "Unable to locate Sign at (x, y, z)" left inside Minecraft Client