Internal Server Error installing

Hello everyone,
I have some issues setting up my blog. I’m not newbie to wordpress and php. The problem is this: when I upload all wp files on my server – once edited the config file – and try to access to the index.php or the wp-admin/install.php files I come across an Internal Server Error.

If I try to access files like readme.html, everything’s fine with them and they are shown properly. Looking for a solution, I came across with tips like checking files&directory chmod, but at my eyes everythings looks ok with my setup. I just cant access the php files in the directory in which I uploaded my wordpress.

Any input/tip?
Thanks in advance,

Giorgio

[EDIT: I’m Using WP vers. 2.1.3]