I am checking your diagnose page, and your server is in fact very powerful. However, it is missing the
mod_rewrite feature:
http://www.abertrande.com/x3/diag/
If you scroll to bottom of the page in the above link, you will also see we are running a test to check for a very basic rewrite of an image path, and as you can see, it is not working ...
viewtopic.php?f=51&t=8339&start=0
We did in fact release a new beta version today which doesn't rely on mod_rewrite for loading assets (css, js, etc), and this would likely make your start-page work. However, without mod_rewrite, X3 would still not function properly when anyone tries to access sub pages like /x3/examples/ etc.
Who is your host? Can you ask them about mod_rewrite? It seems it is not enabled ...