editing any wp-pages

when I try to edit any wp-pages for plugins and such (i/e wp-header.php) -after the edit the main index (site) doesn’t show at all. i/e view levels and category icons and even just editing the wp-comments file.
I have to undo the changes to make the site showup again. It doesn’t seem to matter which wp-file I edit- same result.
specfics: wp1.2,
install dir = http://www.ctfzone.net/zone
public pointer(set though options)= http://www.ctfzone.net
Any help is appreciated.