diff --git a/modules/gallery/controllers/admin_modules.php b/modules/gallery/controllers/admin_modules.php
index 549718e7..46defbef 100644
--- a/modules/gallery/controllers/admin_modules.php
+++ b/modules/gallery/controllers/admin_modules.php
@@ -25,9 +25,48 @@ class Admin_Modules_Controller extends Admin_Controller {
     print $view;
   }
 
+
+  public function confirm() {
+    access::verify_csrf();
+
+    $messages = array("error" => array(), "warn" => array());
+    $desired_list = array();
+    foreach (module::available() as $module_name => $info) {
+      if ($info->locked) {
+        continue;
+      }
+
+      if ($desired = Input::instance()->post($module_name) == 1) {
+        $desired_list[] = $module_name;
+      }
+      if ($info->active && !$desired && module::is_active($module_name)) {
+        $messages = array_merge($messages, module::can_deactivate($module_name));
+      } else if (!$info->active && $desired && !module::is_active($module_name)) {
+        $messages = array_merge($messages, module::check_environment($module_name));
+      }
+    }
+
+    if (empty($messages["error"]) && empty($messages["warn"])) {
+      $this->_do_save();
+      $result["reload"] = 1;
+    } else {
+      $v = new View("admin_modules_confirm.html");
+      $v->messages = $messages;
+      $v->modules = $desired_list;
+      $result["dialog"] = (string)$v;
+      $result["allow_continue"] = empty($messages["error"]);
+    }
+    print json_encode($result);
+  }
+
   public function save() {
     access::verify_csrf();
 
+    $this->_do_save();
+    url::redirect("admin/modules");
+  }
+
+  private function _do_save() {
     $changes->activate = array();
     $changes->deactivate = array();
     $activated_names = array();
@@ -45,6 +84,7 @@ class Admin_Modules_Controller extends Admin_Controller {
       } else if (!$info->active && $desired && !module::is_active($module_name)) {
         $changes->activate[] = $module_name;
         $activated_names[] = t($info->name);
+
         if (module::is_installed($module_name)) {
           module::upgrade($module_name);
         } else {
@@ -63,7 +103,6 @@ class Admin_Modules_Controller extends Admin_Controller {
     if ($deactivated_names) {
       message::success(t("Deactivated: %names", array("names" => join(", ", $deactivated_names))));
     }
-    url::redirect("admin/modules");
   }
 }
 
diff --git a/modules/gallery/helpers/module.php b/modules/gallery/helpers/module.php
index 6c7078a3..2ae83f0d 100644
--- a/modules/gallery/helpers/module.php
+++ b/modules/gallery/helpers/module.php
@@ -119,6 +119,36 @@ class module_Core {
     return self::$active;
   }
 
+  /**
+   * Check that the module can be installed. (i.e. all the prerequistes exist)
+   * @param string $module_name
+   */
+  static function check_environment($module_name) {
+    module::_add_to_path($module_name);
+    $messages = array();
+
+    $installer_class = "{$module_name}_installer";
+    if (method_exists($installer_class, "check_environment")) {
+      $messages = call_user_func(array($installer_class, "check_environment"));
+    }
+
+    // Now the module is installed but inactive, so don't leave it in the active path
+    module::_remove_from_path($module_name);
+    return $messages;
+  }
+
+  /**
+   * Check that the module can be installed. (i.e. all the prerequistes exist)
+   * @param string $module_name
+   */
+  static function can_deactivate($module_name) {
+    $data = (object)array("module" => $module_name, "messages" => array());
+
+    module::event("pre_deactivate", $data);
+
+    return $data->messages;
+  }
+
   /**
    * Install a module.  This will call <module>_installer::install(), which is responsible for
    * creating database tables, setting module variables and calling module::set_version().
@@ -126,13 +156,8 @@ class module_Core {
    * @param string $module_name
    */
   static function install($module_name) {
-    $config = Kohana_Config::instance();
-    $kohana_modules = $config->get("core.modules");
-    array_unshift($kohana_modules, MODPATH . $module_name);
-    $config->set("core.modules",  $kohana_modules);
+    module::_add_to_path($module_name);
 
-    // Rebuild the include path so the module installer can benefit from auto loading
-    Kohana::include_paths(true);
     $installer_class = "{$module_name}_installer";
     if (method_exists($installer_class, "install")) {
       call_user_func_array(array($installer_class, "install"), array());
@@ -142,13 +167,32 @@ class module_Core {
     module::load_modules();
 
     // Now the module is installed but inactive, so don't leave it in the active path
-    array_shift($kohana_modules);
-    $config->set("core.modules",  $kohana_modules);
+    module::_remove_from_path($module_name);
 
     log::success(
       "module", t("Installed module %module_name", array("module_name" => $module_name)));
   }
 
+  private static function _add_to_path($module_name) {
+    $config = Kohana_Config::instance();
+    $kohana_modules = $config->get("core.modules");
+    array_unshift($kohana_modules, MODPATH . $module_name);
+    $config->set("core.modules",  $kohana_modules);
+    // Rebuild the include path so the module installer can benefit from auto loading
+    Kohana::include_paths(true);
+  }
+
+  private static function _remove_from_path($module_name) {
+    $config = Kohana_Config::instance();
+    $kohana_modules = $config->get("core.modules");
+    if (($key = array_search(MODPATH . $module_name, $kohana_modules)) !== false) {
+      unset($kohana_modules[$key]);
+      $kohana_modules = array_values($kohana_modules); // reindex
+    }
+    $config->set("core.modules",  $kohana_modules);
+    Kohana::include_paths(true);
+  }
+
   /**
    * Upgrade a module.  This will call <module>_installer::upgrade(), which is responsible for
    * modifying database tables, changing module variables and calling module::set_version().
@@ -194,10 +238,7 @@ class module_Core {
    * @param string $module_name
    */
   static function activate($module_name) {
-    $config = Kohana_Config::instance();
-    $kohana_modules = $config->get("core.modules");
-    array_unshift($kohana_modules, MODPATH . $module_name);
-    $config->set("core.modules",  $kohana_modules);
+    module::_add_to_path($module_name);
 
     $installer_class = "{$module_name}_installer";
     if (method_exists($installer_class, "activate")) {
diff --git a/modules/gallery/views/admin_modules.html.php b/modules/gallery/views/admin_modules.html.php
index aebedf09..7f572411 100644
--- a/modules/gallery/views/admin_modules.html.php
+++ b/modules/gallery/views/admin_modules.html.php
@@ -1,12 +1,50 @@
 <?php defined("SYSPATH") or die("No direct script access.") ?>
 <div class="g-block ui-helper-clearfix">
+  <script type="text/javascript">
+  $("#g-module-update-form").ready(function() {
+    $("#g-module-update-form").ajaxForm({
+      dataType: "json",
+      success: function(data) {
+        if (data.reload) {
+          window.location.reload();
+        } else {
+          $("body").append('<div id="g-dialog">' + data.dialog + '</div>');
+          $("#g-dialog").dialog({
+            bgiframe: true,
+            autoOpen: true,
+            autoResize: true,
+            modal: true,
+            resizable: false,
+            height: 400,
+            width: 500,
+            position: "center",
+            title: "Confirm Module Activation",
+            buttons: {
+              "Continue": function() {
+                $("form", this).submit();
+              },
+              Cancel: function() {
+                $(this).dialog("destroy").remove();
+              }
+            }
+          });
+          if (!data.allow_continue) {
+            $(".ui-dialog-buttonpane button:contains(Continue)")
+              .attr("disabled", "disabled")
+              .addClass("ui-state-disabled");
+          }
+        }
+      }
+    });
+  });
+  </script>
   <h1> <?= t("Gallery Modules") ?> </h1>
   <p>
     <?= t("Power up your Gallery by adding more modules! Each module provides new cool features.") ?>
   </p>
 
   <div class="g-block-content">
-    <form method="post" action="<?= url::site("admin/modules/save") ?>">
+    <form id="g-module-update-form" method="post" action="<?= url::site("admin/modules/confirm") ?>">
       <?= access::csrf_form_field() ?>
       <table>
         <tr>
diff --git a/modules/gallery/views/admin_modules_confirm.html.php b/modules/gallery/views/admin_modules_confirm.html.php
new file mode 100644
index 00000000..59592505
--- /dev/null
+++ b/modules/gallery/views/admin_modules_confirm.html.php
@@ -0,0 +1,22 @@
+<?php defined("SYSPATH") or die("No direct script access.") ?>
+<div class="ui-helper-clearfix">
+  <p>
+    <?= t("The following issue(s) have been identified:") ?>
+  </p>
+
+  <div id="g-admin-modules-messages" class="g-block-content">
+   <ul>
+     <? foreach (array("error" => "g-error", "warn" => "g-warning") as $type => $class): ?>
+     <? foreach ($messages[$type] as $message): ?>
+     <li class="<?= $class ?>" style="padding-bottom: 0"><?= $message ?></li>
+     <? endforeach ?>
+     <? endforeach ?>
+   </ul>
+    <form method="post" action="<?= url::site("admin/modules/save") ?>">
+      <?= access::csrf_form_field() ?>
+      <? foreach ($modules as $module): ?>
+        <?= form::hidden($module, 1) ?>
+      <? endforeach ?>
+    </form>
+  </div>
+</div>