Wordpress commenting failure

[stanleyek53]

Hello
I was hoping that everything will be okay. I've tested the same version of Wordpress on another hosting, with the same template and without any big changes in configuration.
And there's one! :-(
I'm currently have a problem with posting comments on my site (www.thetomato.eu). If I try to insert a comment under article wordpress is redirecting me to http://thetomato.eu/wp-comments-post.php which is Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, no-reply@x10hosting.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

I have absolutely no idea why I'm experiencing such problem.
This the same site on another hosting - www.informacje.000a.biz, comments works just fine. Default template is not working too. Turning off all of the plugins too.
Please help me! I've searched nearly a half of the Internet and still I can't find the answer.
This is a few things that I've checked before writing this post:
- mysql problem (phpmyadmin repairing)
- last blank line in php files
- turning off the akismet
I don't remember but I've tried a lot of different solutions but none of them is working for me.
Thanks!