Hi,
It seems ok in FF on our demo site. Most likely a skin/design issue.
Make sure you read and apply any needed changes from the Important Skin Changes article.
Use browser dev tools and check the console to make sure there are no javascript errors happening on the page.
Copy one of the newer skins from /Data/skins into your site skin folder and try it with your site to see if you experience the same problem or if it only happens in your skin.
If it only happens in your skin then use Firefox and firebug to inspect the html and css. Possibly you have white text on a white background or something like that but the message is really there.
Hope that helps,
Joe