This is actually more of a continuation of bug #7234 http://tracker.moodle.org/browse/MDL-7234, but I didn't see a way to attach an additional Moodle version number to the bug.

This bug now occurs on 1.7 final. I currently have 3 installations on our server, with the following results:
1.6.3 == the emoticons page does NOT display; this installation has been upgraded several times – the previous version was 1.6.1 and I did not experience this issue
1.7 beta == the emoticons page DOES display; this installation is a fresh copy
1.7 final == the emoticons page does NOT display; this installation is a fresh copy

All 3 of these installations are under the same parent directory (different subdirectory), with their data folders being in the same parent directory (different subdirectory) with each other. Everything about these installations is identical in terms of permissions, config, location, etc.