diff --git a/Gemfile.lock b/Gemfile.lock
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -78,7 +78,7 @@
       treetop (~> 1.4.8)
     mime-types (1.25.1)
     multi_json (1.10.1)
-    mysql2 (0.3.19)
+    mysql2 (0.3.20)
     polyglot (0.3.5)
     power_assert (0.2.2)
     prototype-rails (3.2.1)
diff --git a/app/controllers/configurations_controller.rb b/app/controllers/configurations_controller.rb
--- a/app/controllers/configurations_controller.rb
+++ b/app/controllers/configurations_controller.rb
@@ -16,7 +16,7 @@
 
   def update
     @config = GraderConfiguration.find(params[:id])
-    User.clear_last_login if @config.key = 'multiple_ip_login' and @config.value == 'true' and params[:grader_configuration][:value] == 'false'
+    User.clear_last_login if @config.key == GraderConfiguration::MULTIPLE_IP_LOGIN_KEY and @config.value == 'true' and params[:grader_configuration][:value] == 'false'
     respond_to do |format|
       if @config.update_attributes(params[:grader_configuration])
         format.json { head :ok }
diff --git a/app/controllers/graders_controller.rb b/app/controllers/graders_controller.rb
--- a/app/controllers/graders_controller.rb
+++ b/app/controllers/graders_controller.rb
@@ -86,6 +86,9 @@
     @formatted_code = formatter.format(lexer.lex(@submission.source))
     @css_style = Rouge::Themes::ThankfulEyes.render(scope: '.highlight')
 
+    user = User.find(session[:user_id])
+    SubmissionViewLog.create(user_id: session[:user_id],submission_id: @submission.id) unless user.admin?
+
   end
 
   # various grader controls
diff --git a/app/controllers/problems_controller.rb b/app/controllers/problems_controller.rb
--- a/app/controllers/problems_controller.rb
+++ b/app/controllers/problems_controller.rb
@@ -163,7 +163,7 @@
     @submissions.find_each do |sub|
       d = (DateTime.now.in_time_zone - sub.submitted_at) / 24 / 60 / 60
       @histogram[:data][d.to_i] += 1 if d < range
-      user[sub.user_id] = [user[sub.user_id], (sub.try(:points) >= @problem.full_score) ? 1 : 0].max
+      user[sub.user_id] = [user[sub.user_id], ((sub.try(:points) || 0) >= @problem.full_score) ? 1 : 0].max
     end
     @histogram[:summary][:max] = [@histogram[:data].max,1].max
 
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -125,7 +125,7 @@
 
       @summary[:count] += 1
       next unless sub.problem
-      problem[sub.problem] = [problem[sub.problem], (sub.points >= sub.problem.full_score) ? 1 : 0].max
+      problem[sub.problem] = [problem[sub.problem], ( (sub.try(:points) || 0) >= sub.problem.full_score) ? 1 : 0].max
     end
 
     @histogram[:summary][:max] = [@histogram[:data].max,1].max
diff --git a/app/models/grader_configuration.rb b/app/models/grader_configuration.rb
--- a/app/models/grader_configuration.rb
+++ b/app/models/grader_configuration.rb
@@ -9,6 +9,7 @@
   TEST_REQUEST_EARLY_TIMEOUT_KEY = 'contest.test_request.early_timeout'
   MULTICONTESTS_KEY = 'system.multicontests'
   CONTEST_TIME_LIMIT_KEY = 'contest.time_limit'
+  MULTIPLE_IP_LOGIN_KEY = 'right.multiple_ip_login'
 
   cattr_accessor :config_cache
   cattr_accessor :task_grading_info_cache
diff --git a/app/models/submission_view_log.rb b/app/models/submission_view_log.rb
new file mode 100644
--- /dev/null
+++ b/app/models/submission_view_log.rb
@@ -0,0 +1,3 @@
+class SubmissionViewLog < ActiveRecord::Base
+  attr_accessible :submission_id, :user_id
+end
diff --git a/app/views/report/cheat_scruntinize.html.haml b/app/views/report/cheat_scruntinize.html.haml
new file mode 100644
--- /dev/null
+++ b/app/views/report/cheat_scruntinize.html.haml
@@ -0,0 +1,82 @@
+- content_for :header do
+  = stylesheet_link_tag 'tablesorter-theme.cafe'
+  = javascript_include_tag 'local_jquery'
+
+%script{:type=>"text/javascript"}
+  $(function () {
+  $('#since_datetime').datetimepicker({ showButtonPanel: true, dateFormat: "yy-mm-dd", controlType: "slider"} );
+  $('#until_datetime').datetimepicker({ showButtonPanel: true, dateFormat: "yy-mm-dd", controlType: "slider"} );
+  $('#my_table').tablesorter({widthFixed: true, widgets: ['zebra']});
+  $('#my_table2').tablesorter({widthFixed: true, widgets: ['zebra']});
+  $('#sub_table').tablesorter({widthFixed: true, widgets: ['zebra']});
+  });
+
+%h1 Login status
+
+=render partial: 'report_menu'
+
+
+= form_tag({session: :url })  do
+  .submitbox
+    %table
+      %tr
+        %td{colspan: 6, style: 'font-weight: bold'}= 'Query login & submit in the range'
+      %tr
+        %td{style: 'width: 120px; font-weight: bold'}= 'Login date range'
+        %td{align: 'right'} since:
+        %td= text_field_tag 'since_datetime', @since_time
+      %tr
+        %td
+        %td{align: 'right'} until:
+        %td= text_field_tag 'until_datetime', @until_time
+      %tr
+        %td
+        %td
+        %td Blank mean no condition
+      %tr
+        %td{style: 'width: 120px; font-weight: bold'}= "ID"
+        %td{colspan: 2}= text_field_tag 'SID', @sid, size: 40
+      %tr
+        %td
+        %td
+        %td= submit_tag 'query'
+
+
+%h2 Logs
+
+- if @sid
+  %table
+    %tbody
+      - @sid.each do |id|
+        - user = User.where("login = ?",id).first
+        %tr
+          //%td= link_to id, controller: :user, action: :profile, id: id
+          %td= link_to id, "https://www.nattee.net/java/users/profile/#{user.id}"
+          %td= user.full_name
+
+//%table.tablesorter-cafe#my_table
+%table.info
+  %thead
+    %tr.info-head
+      %th Time
+      %th Action
+      %th IP
+      %th login
+      %th name
+      %th problem
+      %th score
+  %tbody
+    - if @logs
+      - @logs.each do |l|
+        %tr{class: cycle('info-even','info-odd')}
+          %td= l[:submitted_at].strftime "%Y.%b.%d %H:%M:%S"
+          //%td= l[:id] == -1 ? "LOGIN" : link_to("submit #{l[:id]}", controller: 'graders' , action: 'submission', id: l[:id])
+          %td= l[:id] == -1 ? "LOGIN" : link_to( "submit #{l[:id]}", "https://www.nattee.net/java/graders/submission/#{l[:id]}")
+          %td= l[:ip_address]
+          //%td= link_to l[:login], controller: 'users', action: 'profile', id: l[:id]
+          %td= link_to( l[:login], "https://www.nattee.net/java/users/profile/#{l.user_id}")
+          %td= l[:full_name]
+          %td= l[:id] == -1 ? "" : l.problem.name
+          %td= l[:id] == -1 ? "" : l.points * 100/ l.problem.full_score
+
+
diff --git a/app/views/users/profile.html.haml b/app/views/users/profile.html.haml
--- a/app/views/users/profile.html.haml
+++ b/app/views/users/profile.html.haml
@@ -58,7 +58,7 @@
         %td= s.language.pretty_name
         %td  #{s.submitted_at.strftime('%Y-%m-%d %H:%M')} (#{time_ago_in_words(s.submitted_at)} ago)
         %td.fix-width= s.grader_comment
-        %td= (s.points*100)/s.problem.full_score
+        %td= ( s.try(:points) ? (s.points*100/s.problem.full_score)  : '' )
         - if session[:admin]
           %td= s.ip_address
 
diff --git a/db/migrate/20150827131927_create_submission_view_logs.rb b/db/migrate/20150827131927_create_submission_view_logs.rb
new file mode 100644
--- /dev/null
+++ b/db/migrate/20150827131927_create_submission_view_logs.rb
@@ -0,0 +1,10 @@
+class CreateSubmissionViewLogs < ActiveRecord::Migration
+  def change
+    create_table :submission_view_logs do |t|
+      t.integer :user_id
+      t.integer :submission_id
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20150827133841_add_last_ip_to_user.rb b/db/migrate/20150827133841_add_last_ip_to_user.rb
new file mode 100644
--- /dev/null
+++ b/db/migrate/20150827133841_add_last_ip_to_user.rb
@@ -0,0 +1,5 @@
+class AddLastIpToUser < ActiveRecord::Migration
+  def change
+    add_column :users, :last_ip, :string
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20150618085823) do
+ActiveRecord::Schema.define(:version => 20150827133841) do
 
   create_table "announcements", :force => true do |t|
     t.string   "author"
@@ -159,6 +159,13 @@
     t.string   "password"
   end
 
+  create_table "submission_view_logs", :force => true do |t|
+    t.integer  "user_id"
+    t.integer  "submission_id"
+    t.datetime "created_at",    :null => false
+    t.datetime "updated_at",    :null => false
+  end
+
   create_table "submissions", :force => true do |t|
     t.integer  "user_id"
     t.integer  "problem_id"
diff --git a/spec/models/submission_view_logs_spec.rb b/spec/models/submission_view_logs_spec.rb
new file mode 100644
--- /dev/null
+++ b/spec/models/submission_view_logs_spec.rb
@@ -0,0 +1,5 @@
+require 'spec_helper'
+
+describe SubmissionViewLogs do
+  pending "add some examples to (or delete) #{__FILE__}"
+end