internal error – server connection terminated

ISE is very generic and can be caused by numerous underlying issues. Here are some thing you can try to solve it:
– Your first step should be checking your site’s error logs for a more specific error message. If you need help locating them, ask your hosting provider to help you with that.
– check with your host if the domain name is configured properly to point to public_html folder
– It may indicate .htaccess issue. Regenerate .htaccess, and be sure the encoding in your text editor is Unicode No BOM
– It may also indicate a problem with the configuration on the server. Usually your hosting company tech support can help.
– it could be problem with the plugins, try resetting the plugins folder by FTP or phpMyAdmin.
– it could be a problem with the theme. Momentarily, try switching to the default twentyeleven theme via FTP by renaming your current theme to rule out any theme specific issue.
– if these steps don’t help, download WordPress again and replace your copies of everything EXCEPT the wp-config.php file and the /wp-content/ directory with fresh copies. This should replace your core files without changing your content and settings in wp-config.php file and the /wp-content/ directory.