Posting Problem

Howdy fellas. Ever since I installed WordPress a month ago, we’ve been having problems posting blogs and comments. What usually happened was that there was an error message of the generic variety, in other words the ol’ 404 PHP error. What happens now is even more interesting. When I post something, firefox pops up a window informing me that I want to open the file “post.php” and whether I want to open it or save it. Now, the post attempt always works mind you. There’s a delay, and often just a blank screen afterwards, but if we go and look at the site, the post is there. This is not a database issue, because we can add material to the database in any other area such as new links or users, and there’s no problem. It also happens regardless of whether I’m doing something as site admin, or a regular author is doing something. So I don’t think it’s a permissions issue. Any help would be greatly appreciated.