SQL ERROR: Unable to do_query: DELETE FROM w3t_Online WHERE O_Last <
You have an error in your SQL syntax near '' at line 4: 2000

Here's what it is:
// Delete the inactive users
$html = new html;
// $Outdated = $html -> get_date();
// $Outdated = $Outdated - 600;
$Outdated = time() - 600;
$query = "
DELETE FROM w3t_Online
WHERE O_Last < $Outdated
";
$dbh -> do_query($query);

What other files other than online.php do this:
DELETE FROM w3t_Online WHERE O_Last ...

?

This is the only file that does this command.