yes, thats an administrator thing, done in "preferences"
I think it will force all avatars (the little images below the poster's name) to be resized to a fixed size, - even if it was smaller, so its a good thing to enforce early on.
I have thus set a 100 pixel size - but apparently its again one of these style-sheet things that internet Explorer does not interpret correctly. Mozilla on both Windows and Unix looks fine. :-/
What can I say ?! - download Mozilla-Firebird for free at http://www.mozilla.org/products/firebird/
it even allows you to deny popups, and has a brilliant "adblock" plugin, so you can weed out all the banner-ads from your favourite website .-)