Visual/HTML Editor not working properly

So I just re-installed my WP (2.6) after loosing all my server data (but that’s another sad story) now I just found out that when I want to make a new post the visual editor is selected but showing the HTML tools, and when trying to go to HTML it wont load the tools.

The page also prompts an error on line 4 file post-new.php

I even downloaded the whole WP and replace this file but nothing changes. I’ve been looking for someone with the same problem but nothing… I also use FF and IE8 and both show the same problem.

The post-new.php file from the past version (2.5) has a little difference at the start of the code.

Insted of:

wp_enqueue_script('thickbox');

now it shows:

add_thickbox();

I dont know where the problem is so here is a screen shot from what I see.

Thanks in advance