diff --git a/src/Main/Base/Project/Src/Gui/Pads/ProjectBrowser/TreeNodes/DirectoryNode.cs b/src/Main/Base/Project/Src/Gui/Pads/ProjectBrowser/TreeNodes/DirectoryNode.cs
index bbdf7e5080..dc5c3b4ef9 100644
--- a/src/Main/Base/Project/Src/Gui/Pads/ProjectBrowser/TreeNodes/DirectoryNode.cs
+++ b/src/Main/Base/Project/Src/Gui/Pads/ProjectBrowser/TreeNodes/DirectoryNode.cs
@@ -594,18 +594,21 @@ namespace ICSharpCode.SharpDevelop.Project
 			ProjectService.SaveSolution();
 		}
 		
-		public void CopyDirectoryHere(string fileName, bool performMove)
+		public void CopyDirectoryHere(string directoryName, bool performMove)
 		{
-			AddExistingItemsToProject.CopyDirectory(fileName, this, true);
+			string copiedName = Path.Combine(Directory, Path.GetFileName(directoryName));
+			if (FileUtility.IsEqualFileName(directoryName, copiedName))
+				return;
+			AddExistingItemsToProject.CopyDirectory(directoryName, this, true);
 			if (performMove) {
 				foreach (IViewContent content in WorkbenchSingleton.Workbench.ViewContentCollection) {
 					if (content.FileName != null &&
-					    FileUtility.IsBaseDirectory(fileName, content.FileName))
+					    FileUtility.IsBaseDirectory(directoryName, content.FileName))
 					{
-						content.FileName = FileUtility.RenameBaseDirectory(content.FileName, fileName, Path.Combine(this.directory, Path.GetFileName(fileName)));
+						content.FileName = FileUtility.RenameBaseDirectory(content.FileName, directoryName, Path.Combine(this.directory, Path.GetFileName(directoryName)));
 					}
 				}
-				FileService.RemoveFile(fileName, true);
+				FileService.RemoveFile(directoryName, true);
 			}
 		}
 		
diff --git a/src/Main/Base/Project/Src/Project/MSBuildEngine.cs b/src/Main/Base/Project/Src/Project/MSBuildEngine.cs
index 0358a566a6..99f20c7040 100644
--- a/src/Main/Base/Project/Src/Project/MSBuildEngine.cs
+++ b/src/Main/Base/Project/Src/Project/MSBuildEngine.cs
@@ -207,6 +207,9 @@ namespace ICSharpCode.SharpDevelop.Project
 						results.NativeCompilerReturnValue = 0;
 					else
 						results.NativeCompilerReturnValue = 1;
+				} catch (ArgumentException ex) {
+					results.NativeCompilerReturnValue = -2;
+					results.Errors.Add(new CompilerError(null, -1, -1, "", ex.Message));
 				} catch (InvalidProjectFileException ex) {
 					results.NativeCompilerReturnValue = -2;
 					results.Errors.Add(new CompilerError(ex.ProjectFile, ex.LineNumber, ex.ColumnNumber, ex.ErrorCode, ex.Message));