This isn't really a drastic problem, it just looks strange. I've also tried it on a different computer, and with my screen resoultion set to both 1024x768 and 800x600, but it looks the same. I'm using Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.12) Gecko/20050915 Firefox/1.0.7

<URL:stuff/splitbuttons.gif>

Edit: I'm talking about the buttons at the bottom of the message box, as seen in the picture, the list Members you have recieved messages from as such boxes.