problem: 500 internal server error at the site

[eluser]Unknown[/eluser]
Hello,
I've created a website at localhost and It works fine at it.
but when I uploaded it to real site, this message appeared:

Internal Server Error

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

Please contact the server administrator, [email protected] 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 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

by the way, I removed index.php from the links.
and when I delete .htaccess and rewrite 'index.php' in config file, the site works good.
any solv??