Strange behaviour: main category broken

hi,
as I already wrote on my site, all in a sudden, the main category stopped working, meaning: neither do I get a page if I use the mod_rewrite-based URL nor if I use the ugly GET-version (index.php?cat=1). I’ve changed the default category by now to another one, but that didnt help. The problem is still there.
What I did to change this problem till now is:
– I’ve added another category called ‘Life & Let Die II’, cat_ID = 13
– moved all posts from main category to this one
– hacked wp-blog-header.php, wp-admin/post.php, wp-admin/edit-form.php and wp-admin/edit-form-advanced.php respective to mentioned cat_ID
– changed default_category in wp_options from ‘1’ to ’13’
– after it didnt work correctly, I tried displaying the data with IE (I’m using Firefox 0.9.3, and it could have been just some false browser rendering), which returned a ‘Server or DNS not found’-error when using the mod_rewrite-URL and loading on forever if I used the crufty way instead.
– so I thought, maybe it had something to do with displaying and the ampersand character, so I changed the category name to ‘Life and Let Die’ (note the ‘and’ instead the ‘&’) – this didnt help either
By now, I dont know what to do – has anybody else experienced this troubles with WordPress 1.2?
thanks in advance,
cu, w0lf.
ps: my site can be found over here: https://alltagsgrauen.fwwd.de