Configure Views times out

Try increasing it first. Then I guess the next thing to try would be to see if there's anywhere it gets stuck in a loop....

Facing the same problem.
Found it stucked on the loop near line 145:

            while (!$finished) {
              $current_handler = get_parent_class($current_handler);
              if ($current_handler == 'views_handler') {
                // We've reached the top; don't add the root class to the list.
                $finished = TRUE;
              }
              else {
                // Add the class. This is going to be redundant in many cases
                // as we'll have either already done this or be about to find
                // it in the data, but this function is only called on an admin
                // page so performance is not an issue.
                $handlers[$handler_type][$current_handler] = $current_handler;
              }
            }

get_parent_class() always return FALSE

The corresponding variables are causing the error are :

$handler = 'views_handler_sort_print_mail_sentcount'
$handler_type = 'sort'

Hope that helps to pinpoint the problem.

Which module is providing this handler, and what is its parent class? If it's not in the hierarchy then that's pretty much a bug in that module.

There's also kind of problems with _markup handlers.
For example I choose views_handler_field_markup handler for some field with html and receive this message:

Notice: Undefined index: format in views_handler_field_markup->construct() (line 21 of /home/u2643/domains/mn.ph.vps-private.net/sites/all/modules/views/handlers/views_handler_field_markup.inc).

Can't see HTML as HTML, I can only see plain text with HTML tags.

Removed accidental bogus html tag