Assuming I can post a screenshot here, this is what's happening when I'm attempting to reply using Firefox:
If it's not clear, the advert that appears in the right had portion of the screen ALSO appears in the reply section I'm attempting to post my reply into, hence not being able to post a reply to anything while logged in via Firefox.
Obviosuly if I'm not allowed to post a screenshot then I'll remove it
Plus the auto correct/dictionary function doesn't appear to work in IE so some of my words may be speelt wrong.