diff --git a/app/models/dmsf_folder.rb b/app/models/dmsf_folder.rb
index 713cfd26..8db10488 100644
--- a/app/models/dmsf_folder.rb
+++ b/app/models/dmsf_folder.rb
@@ -311,31 +311,26 @@ class DmsfFolder < ActiveRecord::Base
 
   def modified
     last_update = updated_at
-    dmsf_folders.each do |subfolder|
-      last_update = subfolder.updated_at if subfolder.updated_at > last_update
-    end
-    dmsf_files.each do |file|
-      last_update = file.updated_at if file.updated_at > last_update
-    end
-    folder_links.each do |folder_link|
-      last_update = folder_link.updated_at if folder_link.updated_at > last_update
-    end
-    file_links.each do |file_link|
-      last_update = file_link.updated_at if file_link.updated_at > last_update
-    end
-    url_links.each do |url_link|
-      last_update = url_link.updated_at if url_link.updated_at > last_update
-    end
+    time = DmsfFolder.where(
+      ['project_id = ? AND dmsf_folder_id = ? AND updated_at > ?',
+       self.project_id, self.id, last_update]).maximum(:updated_at)
+    last_update = time if time
+    time = DmsfFile.where(
+      ['container_id = ? AND container_type = ? AND dmsf_folder_id = ? AND updated_at > ?',
+       self.project_id, 'Project', self.id, last_update]).maximum(:updated_at)
+    last_update = time if time
+    time = DmsfLink.where(
+      ['project_id = ? AND dmsf_folder_id = ? AND updated_at > ?',
+       self.project_id, self.id, last_update]).maximum(:updated_at)
+    last_update = time if time
     last_update
   end
 
   # Number of items in the folder
   def items
-    dmsf_folders.visible.count +
-    dmsf_files.visible.count +
-    folder_links.visible.count +
-    file_links.visible.count +
-    url_links.visible.count
+    dmsf_folders.where(:project_id => self.project_id).visible.count +
+    dmsf_files.visible.where(:container_id => self.project_id).count +
+    dmsf_links.visible.where(:project_id => self.project_id).count
   end
   
   def self.is_column_on?(column)
diff --git a/app/views/dmsf/_file.html.erb b/app/views/dmsf/_file.html.erb
index 2c9bc730..f9601572 100644
--- a/app/views/dmsf/_file.html.erb
+++ b/app/views/dmsf/_file.html.erb
@@ -20,7 +20,7 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 %>
 
-<% wf = DmsfWorkflow.find_by_id(file.last_revision.dmsf_workflow_id) %>
+<% wf = DmsfWorkflow.find_by_id(file.last_revision.dmsf_workflow_id) if file.last_revision.dmsf_workflow_id %>
 
 <td class="dmsf_checkbox"><%= check_box_tag(name, id, false,
   :title => l(:title_check_for_zip_download_or_email), :id => "file_#{id}") %></td>