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 796a295c9b..b73f96d4cd 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
@@ -828,13 +828,15 @@ namespace ICSharpCode.SharpDevelop.Project
 					CopyDirectoryHere(directoryNode, effect == DragDropEffects.Move);
 				} else if (dataObject.GetDataPresent(DataFormats.FileDrop)) {
 					string[] files = (string[])dataObject.GetData(DataFormats.FileDrop);
-					foreach (string fileName in files) {
-						if (System.IO.Directory.Exists(fileName)) {
-							if (!FileUtility.IsBaseDirectory(fileName, Directory)) {
-								CopyDirectoryHere(fileName, false);
+					if (files != null) {
+						foreach (string fileName in files) {
+							if (System.IO.Directory.Exists(fileName)) {
+								if (!FileUtility.IsBaseDirectory(fileName, Directory)) {
+									CopyDirectoryHere(fileName, false);
+								}
+							} else {
+								CopyFileHere(fileName, false);
 							}
-						} else {
-							CopyFileHere(fileName, false);
 						}
 					}
 				}
diff --git a/src/Main/Base/Project/Src/Gui/Workbench/WpfWorkbench.cs b/src/Main/Base/Project/Src/Gui/Workbench/WpfWorkbench.cs
index 123396b869..2a706e7a1c 100644
--- a/src/Main/Base/Project/Src/Gui/Workbench/WpfWorkbench.cs
+++ b/src/Main/Base/Project/Src/Gui/Workbench/WpfWorkbench.cs
@@ -8,6 +8,7 @@ using System.Diagnostics;
 using System.Globalization;
 using System.IO;
 using System.Linq;
+using System.Runtime.InteropServices;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Documents;
@@ -609,13 +610,17 @@ namespace ICSharpCode.SharpDevelop.Gui
 		
 		DragDropEffects GetEffect(IDataObject data)
 		{
-			if (data != null && data.GetDataPresent(DataFormats.FileDrop)) {
-				string[] files = (string[])data.GetData(DataFormats.FileDrop);
-				foreach (string file in files) {
-					if (File.Exists(file)) {
-						return DragDropEffects.Link;
+			try {
+				if (data != null && data.GetDataPresent(DataFormats.FileDrop)) {
+					string[] files = (string[])data.GetData(DataFormats.FileDrop);
+					foreach (string file in files) {
+						if (File.Exists(file)) {
+							return DragDropEffects.Link;
+						}
 					}
 				}
+			} catch (COMException) {
+				// Ignore errors getting the data (e.g. happens when dragging attachments out of Thunderbird)
 			}
 			return DragDropEffects.None;
 		}