diff --git a/app/controllers/user_admin_controller.rb b/app/controllers/user_admin_controller.rb
--- a/app/controllers/user_admin_controller.rb
+++ b/app/controllers/user_admin_controller.rb
@@ -521,7 +521,7 @@
             row << sc[i].login
             row << sc[i].full_name
             row << sc[i].activated
-            row << (sc[i].try(:contest_stat).try(:started_at)!=nil ? 'yes' : 'no')
+            row << (sc[i].try(:contest_stat).try(:started_at).nil? 'no' : 'yes')
             row << sc[i].contests.collect {|c| c.name}.join(', ')
           else
             row << sc[i][0]
diff --git a/app/views/main/_announcement.html.haml b/app/views/main/_announcement.html.haml
--- a/app/views/main/_announcement.html.haml
+++ b/app/views/main/_announcement.html.haml
@@ -1,7 +1,7 @@
 %li.list-group-item
   %strong
     = announcement.title
-  - if @current_user.admin?
+  - if @current_user and @current_user.admin?
     = link_to 'Edit', edit_announcement_path(announcement), class: 'btn btn-xs btn-default'
   %small= "(updated #{time_ago_in_words(announcement.updated_at)} ago on #{announcement.updated_at})"
 
diff --git a/app/views/main/_submission_short.html.haml b/app/views/main/_submission_short.html.haml
--- a/app/views/main/_submission_short.html.haml
+++ b/app/views/main/_submission_short.html.haml
@@ -2,15 +2,15 @@
 - if submission.nil?
   = "-"
 - else
-  - if submission.graded_at.nil?
-    = t 'main.submitted_at'
+  - unless submission.graded_at
+    =t 'main.submitted_at'
     = format_short_time(submission.submitted_at.localtime)
   - else
     %strong= t 'main.graded_at'
     = "#{format_short_time(submission.graded_at.localtime)} "
     %br
     - if GraderConfiguration['ui.show_score']
-      %strong= t 'main.score'
+      =t 'main.score'
       = "#{(submission.points*100/submission.problem.full_score).to_i} "
     = " [" 
     %tt