When you try to view a task with no due date you get an error 500. You can fix it by changing line 16 on 'application/views/task/task_list.php' from:
<?php if ($task_list->getDueDate()->getYear() > DateTimeValueLib::now()->getYear()) { ?>
<div class="dueDate"><span><?php echo lang('due date') ?>: </span><?php echo format_date($task_list->getDueDate(), null, 0) ?></div>
<?php } else { ?>
<div class="dueDate"><span><?php echo lang('due date') ?>: </span><?php echo format_descriptive_date($task_list->getDueDate(), 0) ?></div>
to:
<?php if ($task_list->getDueDate() instanceof DateTimeValue) { ?>
<?php if ($task_list->getDueDate()->getYear() > DateTimeValueLib::now()->getYear()) { ?>
<div class="dueDate"><span><?php echo lang('due date') ?>: </span><?php echo format_date($task_list->getDueDate(), null, 0) ?></div>
<?php } else { ?>
<div class="dueDate"><span><?php echo lang('due date') ?>: </span><?php echo format_descriptive_date($task_list->getDueDate(), 0) ?></div>
<?php } // if ?>
<?php } // if ?>
This will be fixed on 1.2 RC2.