You are not alone, Bristol. ;) I am currently on a Mac with Safari and I can't post replies, not with Quick reply nor with the Full editor... This sucks. I like the shine (though I don't like that I have to scroll a LOT more on the new forum!) but not being able to reply defeats the purpose of a forum... ;)
Most people seem to be able to reply though... odd...
EDIT
Luckily EDIT still works LOL!!! I see more reports coming in about not being able to reply so it must be a temporary little problem, the kind you get when you switch to new forum software. ;)