Very annoying bug
Maps of the Nether will also freeze upon entering the Nether.
Using maps to build Nether shortcut networks involves a whole lot of disconnect/reconnect.
When I run the script, I get a bunch of errors: http://pastebin.com/2HNZe0e2
Yep, what William Pearson demonstrated is exactly what I am experiencing.
In vanilla, you might be able to see the markers stacking out behind the frame