Re: Strange (?) (404) report i Firebug
Apache processes rewrite directives in the order they are found.
First the main Apache config file is used, then (if they are allowed) the .htaccess files are used in the order they are encountered from the root of the website out through the directories until the final directory that contains the file that is being accessed.
So if you have a page at http://www.example.com/blog/forum, then the order of processing is like:
So the “blog” rewrite rules will be assessed first. This means that you may want to place your bbPress rewrite rules in the same .htaccess file as your blog rules, before the blog rules, as they are more specific and should be handled first.
Also, there were some problems with WordPress throwing 404 errors based on what mod_rewrite was doing. This was specifically with version 2.1 I think, so your WordPress may need to be upgraded.