I've discovered a compatibility issue with the simplepress forum plugin.
Everything works fine except the topic creation. Well I can basically start a new topic but the form doesn't display the validation button (neither the smileys) which prevent me from creating a new thread.
It works fine though when I'm in "Reply" mode.
I've tested this with a clean install of the theme and a clean install of the forum plugin (on a local mode and online). No other modifications and no other plugins installed.
Happy holiday season :)