Error: "htmlspecialchars() expects parameter 1 to be string" when installing plugin

Please, take a look at this, i'm not sure if its a Plugin Manager issue or CTools, but i get several of these error messages when installing a plugin.
It downloads, installs but does not activate. I have to do it manually.

htmlspecialchars() expects parameter 1 to be string, array given in /home/somesite/public_html/dp6/includes/bootstrap.inc on line 840.

Here is the backtrace:

Localização	http://www.somesite.net/dp6/admin/plugin_manager/install
Referência	http://www.somesite.net/dp6/admin/plugin_manager/install
Message	Type: php 

htmlspecialchars() expects parameter 1 to be string, array given in /home/somesite/public_html/dp6/includes/bootstrap.inc on line 840. 

Backtrace:
htmlspecialchars(string)[bootstrap.inc:840];
.check_plain(string)[common.inc:932];
..t(string)[search.inc:257];
...page_manager_search_build_subtask(a:2:{i:0;a:15:{s:9:"task type";s:4:"page";s:5:"title";s:6:"Buscar";s:8:"subtasks";b:1;s:16:"subtask callback";s:27:"page_manager_search_subtask";s:17:"subtasks callback";s:28:"page_manager_search_subtasks";s:15:"hook menu alter";s:30:"page_manager_search_menu_alter";s:12:"handler type";s:7:"context";s:13:"get arguments";s:33:"page_manager_search_get_arguments";s:24:"get context placeholders";s:32:"page_manager_search_get_contexts";s:6:"module";s:12:"page_manager";s:4:"name";s:6:"search";s:4:"path";s:51:"sites/all/modules/ctools/page_manager/plugins/tasks";s:4:"file";s:10:"search.inc";s:13:"plugin module";s:12:"page_manager";s:11:"plugin type";s:5:"tasks";}i:1;s:14:"plugin_manager";})[search.inc:234];
....page_manager_search_subtasks(a:1:{i:0;a:15:{s:9:"task type";s:4:"page";s:5:"title";s:6:"Buscar";s:8:"subtasks";b:1;s:16:"subtask callback";s:27:"page_manager_search_subtask";s:17:"subtasks callback";s:28:"page_manager_search_subtasks";s:15:"hook menu alter";s:30:"page_manager_search_menu_alter";s:12:"handler type";s:7:"context";s:13:"get arguments";s:33:"page_manager_search_get_arguments";s:24:"get context placeholders";s:32:"page_manager_search_get_contexts";s:6:"module";s:12:"page_manager";s:4:"name";s:6:"search";s:4:"path";s:51:"sites/all/modules/ctools/page_manager/plugins/tasks";s:4:"file";s:10:"search.inc";s:13:"plugin module";s:12:"page_manager";s:11:"plugin type";s:5:"tasks";}})[page_manager.module:727];
.....page_manager_get_task_subtasks(a:1:{i:0;a:15:{s:9:"task type";s:4:"page";s:5:"title";s:6:"Buscar";s:8:"subtasks";b:1;s:16:"subtask callback";s:27:"page_manager_search_subtask";s:17:"subtasks callback";s:28:"page_manager_search_subtasks";s:15:"hook menu alter";s:30:"page_manager_search_menu_alter";s:12:"handler type";s:7:"context";s:13:"get arguments";s:33:"page_manager_search_get_arguments";s:24:"get context placeholders";s:32:"page_manager_search_get_contexts";s:6:"module";s:12:"page_manager";s:4:"name";s:6:"search";s:4:"path";s:51:"sites/all/modules/ctools/page_manager/plugins/tasks";s:4:"file";s:10:"search.inc";s:13:"plugin module";s:12:"page_manager";s:11:"plugin type";s:5:"tasks";}})[page_manager.module:152];
......page_manager_menu_alter(string)[?:?];
.......call_user_func_array(string)[common.inc:2839];
........drupal_alter(string)[menu.inc:1737];
.........menu_router_build(a:1:{i:0;b:1;})[menu.inc:1701];
..........menu_rebuild(a:0:{})[plugin_manager.admin.inc:328];
...........plugin_manager_install_2(string)[plugin_manager.admin.inc:353];
............plugin_manager_install_form_submit(string)[form.inc:776];
.............form_execute_handlers(string)[form.inc:416];
..............drupal_process_form(string)[form.inc:119];
...............drupal_get_form(a:1:{i:0;s:27:"plugin_manager_install_form";})[?:?];
................call_user_func_array(a:2:{i:0;s:15:"drupal_get_form";i:1;a:1:{i:0;s:27:"plugin_manager_install_form";}})[menu.inc:348];
.................menu_execute_active_handler(a:0:{})[index.php:18];
..................index.php

Some more info:

Acesso ao update.php	Protegido
Arquivo de configurações	Protegido
Atualizações do banco de dados	Atualizado
Banco de dados MySQL	5.1.41
Biblioteca GD	bundled (2.0.34 compatible)
Biblioteca Unicode	Extensão Mbstring do PHP
CTools CSS Cache	Existente
Image module directories	Exists (sites/default/files/images).
Limite de memória do PHP	128M
Notificações de atualizações	Habilitado
PHP	5.2.9
PHP register globals	Desativado
Servidor web	Apache/2.2.14 (Unix) mod_ssl/2.2.14 OpenSSL/0.9.8e-fips-rhel5 DAV/2 mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635
Sistema de arquivos	Gravável (método de download público)
Toolkit de imagens	The gd toolkit is installed.

Just trying to help. If more info is needed, i'll do my best to provide.