I installed the Kunena Forum on a new site
I first noticed this on my Win7 laptop with IE8 and then started receiving emails from other users that have the same issue. The problem is not repeatable on other sites using Kunena and it does not seem to matter what browser or flavor of Windows they are running.
When a Registered user tries to create a "New Topic" or reply to an existing topic they cannot see anything in the "Category" Drop Down Menu and they cannot type anything in the "Message" area.
This is only an issue with Internet Explorer and it does not seem to matter whether its 6, 7, or 8. However it does work fine on some computers in IE. It also does not matter which flavor of Windows is installed (XP, Vista, or 7).