Code igniter- 500 Internal server Error

I have downloaded Gocar3 codeigniter e-commerce.. and installed to my local server(xampp).. after installation the index page comes with 404 error message with header menu and i tried ti click on login page link the the url goes correctly but the page shows Internal server error.. I searched and tried it by .htaccess issues and Apace rewrite_mod enable..I did all these.. but still th site shows the "Internal Server Error

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

Please contact the server administrator at postmaster@localhost to inform them of the time this error occurred, and the actions you performed just before this 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. Apache/2.4.2 (Win32) OpenSSL/1.0.1c PHP/5.4.4 Server at localhost Port 80"

Please Guys.. do u have any solution for this??

via Chebli Mohamed