Index: Lib/idlelib/idle.py
===================================================================
--- Lib/idlelib/idle.py	(revision 66965)
+++ Lib/idlelib/idle.py	(working copy)
@@ -1,3 +1,7 @@
+import tkMessageBox
+import traceback
+import sys
+
 try:
     import idlelib.PyShell
 except ImportError:
@@ -16,6 +20,16 @@
                 os.environ['PYTHONPATH'] = pypath + ':' + idledir
             else:
                 os.environ['PYTHONPATH'] = idledir
-        PyShell.main()
+        try:
+            PyShell.main()
+        except:
+            err = traceback.format_exc()
+            sys.stdout.write(err)
+            tkMessageBox.showerror("Error", err)
 else:
-    idlelib.PyShell.main()
+    try:
+        idlelib.PyShell.main()
+    except:
+        err = traceback.format_exc()
+        sys.stdout.write(err)
+        tkMessageBox.showerror("Error", err)