Index: Connect.cs
===================================================================
--- Connect.cs	(revision 41291)
+++ Connect.cs	(working copy)
@@ -94,6 +94,12 @@
             else
                 pipeName = PipeNameTextBox.Text;
 
+            if (Type == ConnectionType.Serial && !cPort.Enabled)
+            {
+                MessageBox.Show("Could not find any useable serial port. Use an other connection interface.", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Warning);
+                return;
+            }
+
             if (cType.SelectedItem.ToString().CompareTo("Client") == 0)
                 pipeMode = ConnectionMode.MODE_CLIENT;
             else if (cType.SelectedItem.ToString().CompareTo("Server") == 0)
@@ -112,13 +118,24 @@
             int i = 0;
 
             /* Serial */
-            foreach (string s in SerialPort.GetPortNames())
+            string[] serialPorts = SerialPort.GetPortNames();
+            if (serialPorts == null || serialPorts.Length == 0)
             {
-                cPort.Items.Add(s);
+                cPort.Enabled = false;
+                cBaud.Enabled = false;
+                tabSerial.Text = "Serial (unavailable)";
             }
-            SelectComboItem(cPort, Settings.ComPort);
-            SelectComboItem(cBaud, Settings.Baudrate);
+            else
+            {
+                foreach (string s in serialPorts)
+                {
+                    cPort.Items.Add(s);
+                }
 
+                SelectComboItem(cPort, Settings.ComPort);
+                SelectComboItem(cBaud, Settings.Baudrate);
+            }
+
             /* Pipe */
             DefaultRadioBtn.Text += " [" + defaultPipeName + "]";
             for (i = 0; i < cType.Items.Count - 1; i++)
Index: MainWindow.cs
===================================================================
--- MainWindow.cs	(revision 41291)
+++ MainWindow.cs	(working copy)
@@ -306,6 +306,8 @@
                     switch (newConnection.Type)
                     {
                         case Connect.ConnectionType.Serial:
+                            if (String.IsNullOrEmpty(newConnection.ComPort))
+                                return;
                             mConnection.StartSerial(newConnection.ComPort, newConnection.Baudrate);
                             break;
                         case Connect.ConnectionType.Pipe: