diff --git a/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs b/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs
index 743e02656..0d38e6581 100644
--- a/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs
+++ b/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutAnchorableTabItem.cs
@@ -181,7 +181,8 @@ protected override void OnMouseEnter( MouseEventArgs e )
     {
       base.OnMouseEnter( e );
 
-      if( _draggingItem != this &&
+      if( _draggingItem != null &&
+          _draggingItem != this &&
           e.LeftButton == MouseButtonState.Pressed )
       {
         var model = Model;
diff --git a/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutGridControl.cs b/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutGridControl.cs
index 0f8960d69..cb1c18536 100644
--- a/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutGridControl.cs
+++ b/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Controls/LayoutGridControl.cs
@@ -416,7 +416,8 @@ private void OnSplitterDragCompleted( object sender, System.Windows.Controls.Pri
         else
         {
           var width = ( prevChildModel.DockWidth.IsAuto ) ? prevChildActualSize.Width : prevChildModel.DockWidth.Value;
-          prevChildModel.DockWidth = new GridLength( width + delta, GridUnitType.Pixel );
+          var resizedWidth = width + delta;
+          prevChildModel.DockWidth = new GridLength( double.IsNaN(resizedWidth) ? width : resizedWidth, GridUnitType.Pixel );
         }
 
         if( nextChildModel.DockWidth.IsStar )
@@ -426,7 +427,8 @@ private void OnSplitterDragCompleted( object sender, System.Windows.Controls.Pri
         else
         {
           var width = ( nextChildModel.DockWidth.IsAuto ) ? nextChildActualSize.Width : nextChildModel.DockWidth.Value;
-          nextChildModel.DockWidth = new GridLength( width - delta, GridUnitType.Pixel );
+          var resizedWidth = width - delta;
+          nextChildModel.DockWidth = new GridLength( double.IsNaN(resizedWidth) ? width : resizedWidth, GridUnitType.Pixel );
         }
       }
       else
@@ -438,7 +440,8 @@ private void OnSplitterDragCompleted( object sender, System.Windows.Controls.Pri
         else
         {
           var height = ( prevChildModel.DockHeight.IsAuto ) ? prevChildActualSize.Height : prevChildModel.DockHeight.Value;
-          prevChildModel.DockHeight = new GridLength( height + delta, GridUnitType.Pixel );
+          var resizedHeight = height + delta;
+          prevChildModel.DockHeight = new GridLength( double.IsNaN(resizedHeight) ? height : resizedHeight, GridUnitType.Pixel );
         }
 
         if( nextChildModel.DockHeight.IsStar )
@@ -448,7 +451,8 @@ private void OnSplitterDragCompleted( object sender, System.Windows.Controls.Pri
         else
         {
           var height = ( nextChildModel.DockHeight.IsAuto ) ? nextChildActualSize.Height : nextChildModel.DockHeight.Value;
-          nextChildModel.DockHeight = new GridLength( height - delta, GridUnitType.Pixel );
+          var resizedHeight = height - delta;
+          nextChildModel.DockHeight = new GridLength( double.IsNaN(resizedHeight) ? height : resizedHeight, GridUnitType.Pixel );
         }
       }
 
diff --git a/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Layout/LayoutPositionableGroup.cs b/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Layout/LayoutPositionableGroup.cs
index 9818face0..91d3e5ec2 100644
--- a/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Layout/LayoutPositionableGroup.cs
+++ b/ExtendedWPFToolkitSolution/Src/Xceed.Wpf.AvalonDock/Layout/LayoutPositionableGroup.cs
@@ -50,7 +50,7 @@ public GridLength DockWidth
       }
       set
       {
-        if( DockWidth != value )
+        if( DockWidth != value && value.Value > 0 )
         {
           RaisePropertyChanging( "DockWidth" );
           _dockWidth = value;
@@ -74,7 +74,7 @@ public GridLength DockHeight
       }
       set
       {
-        if( DockHeight != value )
+        if( DockHeight != value && value.Value > 0 )
         {
           RaisePropertyChanging( "DockHeight" );
           _dockHeight = value;