Index: DamClients/DamUI/trunk/src/Dam/Application/Program.cs
===================================================================
diff -u -r6436 -r6903
--- DamClients/DamUI/trunk/src/Dam/Application/Program.cs	(.../Program.cs)	(revision 6436)
+++ DamClients/DamUI/trunk/src/Dam/Application/Program.cs	(.../Program.cs)	(revision 6903)
@@ -20,9 +20,13 @@
 // All rights reserved.
 
 using System;
+using System.Collections.Generic;
 using System.Drawing;
 using System.Text;
+using System.Windows.Forms;
 using Deltares.Dam.Data.License;
+using Deltares.Dam.Data.Registry;
+using Deltares.Dam.Data.Version;
 using Deltares.Dam.Forms;
 using Deltares.Geometry.Forms;
 using Deltares.Geotechnics.Forms;
@@ -61,6 +65,8 @@
 
         private static void Start()
         {
+            VerifyInstallation();
+
             DamLicense.CheckoutLicense(dAuthFeature, info.AssemblyVersion);
 
             // Parameters are used for splash screen
@@ -84,6 +90,55 @@
             DamLicense.CheckinLicense();
         }
 
+        /// <summary>
+        /// Check if the application is properly installed by verifying the required versions
+        /// of Common Files and DS_Flex in the registry.
+        /// If not, show an error message and exit the application.
+        /// </summary>
+        private static void VerifyInstallation()
+        {
+            const string requiredVersionCommonFiles = "26.1";
+            const string registryPathCommonFiles = "SOFTWARE\\WOW6432Node\\Deltares\\";
+            const string registryKeyCommonFiles = "Common Version";
+            const string requiredVersionDsFlex = "7.9";
+            const string registryPathDsFlex = "SOFTWARE\\WOW6432Node\\WL | Delft Hydraulics\\DS_Flex\\";
+            const string registryKeyDsFlex = "InstallerVersion";
+            
+            var errorMessages = new List<string>();
+            // Check version of Common Files
+            string versionCommonFiles = RegistryReader.GetRegistryValueFromLocalMachine(registryPathCommonFiles, registryKeyCommonFiles);
+            if (string.IsNullOrEmpty(versionCommonFiles))
+            {
+                errorMessages.Add("Common Files not found.");
+            } else if (!VersionComparer.IsVersionGreaterOrEqual(versionCommonFiles, requiredVersionCommonFiles))
+            {
+                errorMessages.Add("Common files version is outdated: " + versionCommonFiles + 
+                                  ". Required version is " + requiredVersionCommonFiles + " or higher.");
+            }
+            // Check version of DS_Flex
+            string versionDsFlex = RegistryReader.GetRegistryValueFromLocalMachine(registryPathDsFlex, registryKeyDsFlex);
+            if (string.IsNullOrEmpty(versionCommonFiles))
+            {
+                errorMessages.Add("DS_Flex not found.");
+            } else if (!VersionComparer.IsVersionGreaterOrEqual(versionDsFlex, requiredVersionDsFlex))
+            {
+                errorMessages.Add("DS_Flex version is outdated: " + versionDsFlex + 
+                                  ". Required version is " + requiredVersionDsFlex + " or higher.");
+            }
+            if (errorMessages.Count > 0)
+            {
+                var errorMessage = new StringBuilder();
+                errorMessage.AppendLine("The application cannot be started because it is not properly installed. Please reinstall the application.");
+                foreach (string msg in errorMessages)
+                {
+                    errorMessage.AppendLine(msg);
+                }
+
+                MessageBox.Show(errorMessage.ToString(), "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                Environment.Exit(0);
+            }
+        }
+
         private static void MainFormTextChanged(object sender, EventArgs eventArgs)
         {
             var mainForm = sender as MainForm;