Html表单提交 - 原因没有收到数据ERR_EMPTY_RESPONSE

Alright, Im sorry to ask such a simple question. But I have been set back a few days playing with this stupid form... So I'm going to keep it short.

So Ive tried all types of forms, all with the same problem.

This one I pulled straight from W3Schools and its not working either...

They all cause a new page with: NO DATA RECEIVED, ERR_EMPTY_RESPONSE

EDIT: Tables, User, pass etc... removed for security.

        <?php
        if(isset($_POST['submit']))
        {
        $dbhost = 'localhost';
        $dbuser = '';
        $dbpass = '';
        $conn = mysql_connect($dbhost, $dbuser, $dbpass);
        if(! $conn )
        {
          die('Could not connect: ' . mysql_error());
        }

        if(! get_magic_quotes_gpc() )
        {
           $emp_name = addslashes ($_POST['firstname']);
           $emp_address = addslashes ($_POST['lastname']);
        }
        else
        {
           $emp_name = $_POST['firstname'];
           $emp_address = $_POST['lastname'];
        }

        $sql = "INSERT INTO `` . `` ".
               "(name,img-path) ".
               "VALUES('$emp_name','$emp_address')";
        mysql_select_db('');
        $retval = mysql_query( $sql, $conn );
        if(! $retval )
        {
          die('Could not enter data: ' . mysql_error());
        }
        echo "Entered data successfully
";
        mysql_close($conn);
        }
        else
        {
        ?>
        <form action="add-nexts.php" method="post">
            First name:
            <br>
            <input type="text" name="firstname" value="Mickey">
            <br> Last name:
            <br>
            <input type="text" name="lastname" value="Mouse">
            <br>
            <br>
            <input type="submit" name="submit" id ="submit" value="Submit">
        </form>

        <?php
           }
        ?>

I have no idea what I am doing wrong. Hoping maybe you guys do. Thanks alot guys!

EDIT: Well Ive got my script working with GET. But POSTing is what is causing the problem. If this helps narrow it down for anyone... I will need to use POST when my site goes live. But for now at least I can move forward.

EDIT: Confirmed not my hosting provider.... Can anyone at least tell me what I should do next lol??? Im stumped, and cannot move forward with image uploads and other things!! Very tired of wasting time!!

I encountered the same problem. When I submit a form which has a action="login.php" attribute, it just displayed the errors described by OP. I resolved it by adding <!DOCTYPE html> at the beginning of the file. I'm not sure why however.