9
It may be that a certain 'area' of your site does not have the right width value associated with it (sorry about my layman's language). What I mean is, if for example, the width of your code/quote/comment/post areas is not set correctly, it will distort the whole page when it displays.
have a look in your content.css file, and look for code like this
body#newbb .xoopsCode {max-width: 600px;}
(this example defines the code box width within newbb)
Never let a man who does not believe something can be done, talk to a man that is doing it.