diff --git a/MainWindow.xaml.cs b/MainWindow.xaml.cs
index c7f80c0a..27f99b8b 100644
--- a/MainWindow.xaml.cs
+++ b/MainWindow.xaml.cs
@@ -414,8 +414,12 @@ namespace DICUI
         /// </summary>
         private void SetSupportedDriveSpeed()
         {
-            string driveLetter = cmb_DriveLetter.Text;
-            if (String.IsNullOrWhiteSpace(driveLetter))
+            // Get the drive letter from the selected item
+            var selected = cmb_DriveLetter.SelectedItem as Tuple<char, string>;
+            char driveLetter = selected.Item1;
+
+            // Validate that the required program exits
+            if (!File.Exists(dicPath))
             {
                 return;
             }
diff --git a/Utilities.cs b/Utilities.cs
index eb2b83b2..5fdeb33f 100644
--- a/Utilities.cs
+++ b/Utilities.cs
@@ -1773,7 +1773,7 @@ namespace DICUI
                     {
                         return false;
                     }
-                    else if (dvdspeed < 0 || dvdspeed > 16)
+                    else if (dvdspeed < 0 || dvdspeed > 72) // Officialy, 0-16
                     {
                         return false;
                     }