// I basically threw in some basic diagnostic displays.
// Had no choice since the link to your complete source code
// wasn't working. Anyway, this should help you track down
// your problem. Hopefully.

error_reporting( E_ALL );

// GET SUPER ADMIN
$z_getsuper = mysql_query( "SELECT * FROM members WHERE mem_level = '5'" ) or die( mysql_e
 *rror() );

// Loop through results.
while( $row = mysql_fetch_array( $z_getsuper ) )
{
// Comment this if() statement out or delete it when finished debugging.
if( $row['mem_id'] == 0 )
{
// Output all fields of "faulty" record for troubleshooting.
echo '<p>Error: An ID number of <strong>0</strong> was detected.</p>';

rsort( $row, SORT_NUMERIC );

$i = ( count( $row ) - 1 );

do
{
echo '<p>' . $row[$1] . '</p>';
}
while( $i-- );

die();
}

$z_super_id = $row['mem_id'];

// Construct SQL query separately. Easier to read.
$sql ="INSERT INTO mb_mod_alert SET
mb_mod_alert_receive_id = '$z_super_id',
mb_mod_alert_sender_id = '$l_id',
mb_mod_alert_preset = '$preset',
mb_mod_alert_reason = '$reason',
mb_mod_alert_msg = '$alert_msg',
mb_mod_alert_date = '$rightnow',
mb_mod_alert_status = 'new'";

// Send message to Super Admins.
$sendalertsuper = mysql_query( $sql );

// If message insertion fails, kill script and display debugging info.
// Comment out or delete when finished debugging.
if( mysql_affected_rows() <= 0 )
{
echo '<p><strong>NOTICE:</strong> Could not insert new record into database.</p>';

// If there was an SQL error, we'll display it.
if( mysql_error() )
{
echo '<p><strong>MySQL Error:</strong>' . mysql_error() . '</p>';
}

echo '<p><strong>Your SQL Query:</strong> <span style="color: #696;">' . $sql . '</span></
 *p>';

die();
}
}

(*) WARNING 2 long line(s) split