diff --git a/app/controller/preferences_controller.rb b/app/controller/preferences_controller.rb
index e486642..6135b1c 100644
--- a/app/controller/preferences_controller.rb
+++ b/app/controller/preferences_controller.rb
@@ -57,7 +57,7 @@ def showPathErrorAlert(notification)
     
     alert = NSAlert.alloc.init
     alert.alertStyle = OSX::NSCriticalAlertStyle
-    alert.messageText = "The path '#{path}' doesn't exist.."
+    alert.messageText = "The executable path '#{path}' doesn't exist.\nPlease check your preferences."
     alert.runModal
   end
 end
\ No newline at end of file
diff --git a/app/controller/window_controller.rb b/app/controller/window_controller.rb
index 66151b7..fca2233 100644
--- a/app/controller/window_controller.rb
+++ b/app/controller/window_controller.rb
@@ -13,6 +13,7 @@ def awakeFromNib
   
   def runSpecs(sender)
     return if SpecRunner.command_running?
+    return unless valid_bin_paths?
     path = @pathTextField.stringValue
     return false if path.empty? || !File.exist?(path)
     specRunPreparation(nil)
@@ -92,6 +93,13 @@ def path_is_valid?(path)
     end    
   end
   
+  def valid_bin_paths?
+    return false unless $app.file_exist?($app.default_from_key(:spec_bin_path))
+    return false unless $app.file_exist?($app.default_from_key(:ruby_bin_path))
+    return false unless $app.file_exist?($app.default_from_key(:tm_bin_path))
+    true
+  end
+
   def hook_events
     receive :spec_run_invoked,          :specRunPreparation    
     receive :spec_run_start,            :specRunStarted
diff --git a/spec/controller/window_controller_spec.rb b/spec/controller/window_controller_spec.rb
index 3164dbf..37d389a 100644
--- a/spec/controller/window_controller_spec.rb
+++ b/spec/controller/window_controller_spec.rb
@@ -40,6 +40,8 @@
     
     $app = mock('App')
     $app.stub!(:default_for_key)
+    $app.stub!(:default_from_key)
+    $app.stub!(:file_exist?).and_return(true)
     $spec_list = SpecList.new
     SpecRunner.stub!(:run_in_path).and_return(File.dirname(__FILE__))    
   end
@@ -163,4 +165,14 @@
     @mock_statusLabel.should_receive(:stringValue=).with('')
     @controller.path_is_valid?('/tmp').should be_true
   end
+  
+  it 'should check valid bin paths before running a spec' do
+    @controller.should_receive(:valid_bin_paths?)
+    @controller.runSpecs(nil)
+  end
+  
+  it 'should check all 3 bin paths before spec run' do
+    $app.should_receive(:file_exist?).and_return(false)
+    @controller.valid_bin_paths?.should be_false
+  end
 end
\ No newline at end of file