apache - PHP Error on my website -

i installed wallpaper script on domain gives error on page :

the server encountered internal error or misconfiguration , unable complete request.

please contact server administrator, [no address given] , inform them of time error occurred, , might have done may have caused error.

more information error may available in server error log.

can help? site http://hotwallpapers.pk

sounds apache error resulting malformed or otherwise invalid .htaccess file. recommend checking error.log file, wherever resides. /var/log/httpd/error.log in distributions.)