Joining a group from the user dashboard throws a fatal error IF assigned activities pane is enabled

I get an error message when attempting to join a group from the user contact dashboard. ( ie http://mygroup.org/civicrm/user )

To reproduce this in the public demo:

1) Log in as "demo" then go to: http://drupal.demo.civicrm.org/civicrm/user?reset=1&id=203

2) Use the "Join a Group" area to add yourself to a new group.

You will then see the error message and stack trace below:
#0 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Error.php(315): CRM_Core_Error::backtrace()
#1 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Controller.php(826): CRM_Core_Error::fatal("We can't load the requested web page. This page requires cookies to be enable...")
#2 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Controller.php(821): CRM_Core_Controller->invalidKeyCommon()
#3 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Controller.php(307): CRM_Core_Controller->invalidKey()
#4 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Controller.php(206): CRM_Core_Controller->key("CRM_Activity_Form_Search", TRUE, FALSE)
#5 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Controller/Simple.php(63): CRM_Core_Controller->__construct("Activities", TRUE, NULL, "CRM_Activity_Form_Search", FALSE, FALSE)
#6 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Activity/Page/UserDashboard.php(49): CRM_Core_Controller_Simple->__construct("CRM_Activity_Form_Search", "Activities")
#7 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Activity/Page/UserDashboard.php(72): CRM_Activity_Page_UserDashboard->listActivities()
#8 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Contact/Page/View/UserDashBoard.php(189): CRM_Activity_Page_UserDashboard->run()
#9 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Contact/Page/View/UserDashBoard.php(215): CRM_Contact_Page_View_UserDashBoard->buildUserDashBoard()
#10 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Invoke.php(323): CRM_Contact_Page_View_UserDashBoard->run((Array:2), NULL)
#11 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Invoke.php(72): CRM_Core_Invoke::runItem((Array:14))
#12 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Invoke.php(52): CRM_Core_Invoke::_invoke((Array:2))
#13 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/drupal/civicrm.module(456): CRM_Core_Invoke::invoke((Array:2))
#14 [internal function](): civicrm_invoke("user")
#15 /var/www/drupal7.civicrm.org/public/includes/menu.inc(517): call_user_func_array("civicrm_invoke", (Array:1))
#16 /var/www/drupal7.civicrm.org/public/index.php(21): menu_execute_active_handler()
#17

{main}

Other notes: the unsubscribe/rejoin features are working fine. Also, the above error does not occur if I disable the section "Assigned Activities" using the screen at: http://drupal.demo.civicrm.org/civicrm/admin/setting/preferences/display?reset=1