diff --git a/DDUserManager/DDUserManager/frmMain.vb b/DDUserManager/DDUserManager/frmMain.vb
index 615230f..65d020e 100644
--- a/DDUserManager/DDUserManager/frmMain.vb
+++ b/DDUserManager/DDUserManager/frmMain.vb
@@ -20,84 +20,105 @@ Public Class frmMain
     Private Shared logger As NLog.Logger = NLog.LogManager.GetCurrentClassLogger()
 
     Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles MyBase.Load
-        NLog.LogManager.Configuration = ClassNLog.GetLoggerConfigFor(MODULE_NAME)
+        Try
+            NLog.LogManager.Configuration = ClassNLog.GetLoggerConfigFor(MODULE_NAME)
 
-        logger.Info("Starting UserManager v" & Application.ProductVersion)
-        logger.Info($"Current Username: {Environment.UserName}")
+            logger.Info("Starting UserManager v" & Application.ProductVersion)
+            logger.Info($"Current Username: {Environment.UserName}")
 
-        If InitDatabase() = False Then
-            MsgBox($"Unexpected error in Database Init(1). {vbCrLf & vbCrLf}Please contact Your admin.", MsgBoxStyle.Critical, "UserManager")
-            logger.Fatal($"Unexpected error in Database Init(1). {vbCrLf & vbCrLf}Please contact Your admin.")
-            Application.Exit()
-            Exit Sub
-        End If
-        If MyConnectionString = "" Then
-            MsgBox($"Unexpected error in Database Init(2). {vbCrLf & vbCrLf}Please contact Your admin.", MsgBoxStyle.Critical, "UserManager")
-            logger.Fatal($"Unexpected error in Database Init(2). {vbCrLf & vbCrLf}Please contact Your admin.")
-            Application.Exit()
-            Exit Sub
-        End If
+            If InitDatabase() = False Then
+                MsgBox($"Unexpected error in Database Init(1). {vbCrLf & vbCrLf}Please contact Your admin.", MsgBoxStyle.Critical, "UserManager")
+                logger.Fatal($"Unexpected error in Database Init(1). {vbCrLf & vbCrLf}Please contact Your admin.")
+                Application.Exit()
+                Exit Sub
+            End If
+            If MyConnectionString = "" Then
+                MsgBox($"Unexpected error in Database Init(2). {vbCrLf & vbCrLf}Please contact Your admin.", MsgBoxStyle.Critical, "UserManager")
+                logger.Fatal($"Unexpected error in Database Init(2). {vbCrLf & vbCrLf}Please contact Your admin.")
+                Application.Exit()
+                Exit Sub
+            End If
 
-        TBDD_CLIENTTableAdapter.Connection.ConnectionString = MyConnectionString
-        TBDD_CLIENT_USERTableAdapter.Connection.ConnectionString = MyConnectionString
-        TBDD_GROUPSTableAdapter.Connection.ConnectionString = MyConnectionString
-        TBDD_GROUPS_CLIENTTableAdapter.Connection.ConnectionString = MyConnectionString
-        TBDD_GROUPS_MODULESTableAdapter.Connection.ConnectionString = MyConnectionString
-        TBDD_GROUPS_USERTableAdapter.Connection.ConnectionString = MyConnectionString
-        TBDD_MODULESTableAdapter.Connection.ConnectionString = MyConnectionString
-        TBDD_USERTableAdapter.Connection.ConnectionString = MyConnectionString
-        TBDD_USER_MODULESTableAdapter.Connection.ConnectionString = MyConnectionString
+            TBDD_CLIENTTableAdapter.Connection.ConnectionString = MyConnectionString
+            TBDD_CLIENT_USERTableAdapter.Connection.ConnectionString = MyConnectionString
+            TBDD_GROUPSTableAdapter.Connection.ConnectionString = MyConnectionString
+            TBDD_GROUPS_CLIENTTableAdapter.Connection.ConnectionString = MyConnectionString
+            TBDD_GROUPS_MODULESTableAdapter.Connection.ConnectionString = MyConnectionString
+            TBDD_GROUPS_USERTableAdapter.Connection.ConnectionString = MyConnectionString
+            TBDD_MODULESTableAdapter.Connection.ConnectionString = MyConnectionString
+            TBDD_USERTableAdapter.Connection.ConnectionString = MyConnectionString
+            TBDD_USER_MODULESTableAdapter.Connection.ConnectionString = MyConnectionString
 
+            Dim sql = String.Format("SELECT * FROM [dbo].[FNDD_CHECK_USER_MODULE] ('{0}','UM',{1})", Environment.UserName, 1)
+            Dim DT_CHECKUSER_MODULE As DataTable = clsDatabase.Return_Datatable(sql)
 
-        Dim sql = String.Format("SELECT * FROM [dbo].[FNDD_CHECK_USER_MODULE] ('{0}','UM',{1})", Environment.UserName, 1)
-        Dim DT_CHECKUSER_MODULE As DataTable = clsDatabase.Return_Datatable(sql)
+            If DT_CHECKUSER_MODULE.Rows.Count = 0 Then
+                MsgBox($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt. {vbCrLf & vbCrLf}Bitte kontaktieren Sie den Administrator, wenn dies ein Fehler ist.", MsgBoxStyle.Critical, "UserManager")
+                logger.Warn($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt.")
+                Application.ExitThread()
+            End If
 
-        If DT_CHECKUSER_MODULE.Rows.Count = 1 Then
+            Dim firstRow As DataRow = DT_CHECKUSER_MODULE.Rows.Item(0)
+            Dim userId As Integer = firstRow.Item("USER_ID")
 
+            If userId = 0 Then
+                MsgBox($"Der Benutzer '{Environment.UserName}' ist nicht in der Benutzerverwaltung vorhanden. {vbCrLf & vbCrLf}Bitte kontaktieren Sie den Administrator, wenn dies ein Fehler ist.", MsgBoxStyle.Critical, "UserManager")
+                logger.Warn($"Der Benutzer '{Environment.UserName}' ist nicht in der Benutzerverwaltung vorhanden.")
+                Application.ExitThread()
+            End If
 
-            Dim userRow As TBDD_USERRow = GetCurrentUserRow(Environment.UserName)
+            If DT_CHECKUSER_MODULE.Rows.Count = 1 Then
+                Dim userRow As TBDD_USERRow = GetCurrentUserRow(Environment.UserName)
 
-            tsLabelUser.Text = $"Angemeldeter Benutzer: {Environment.UserName}"
-            tsLabelVersion.Text = $"Version {Application.ProductVersion}"
+                If userRow Is Nothing Then
 
-            lblADRootNode.Text = String.Format(lblADRootNode.Text, Environment.UserDomainName)
-            txtADRootNode.Text = ActiveDirectoryRootNode
+                End If
 
-            CurrentUser = userRow
-            CurrentUserId = userRow.GUID
+                tsLabelUser.Text = $"Angemeldeter Benutzer: {Environment.UserName}"
+                tsLabelVersion.Text = $"Version {Application.ProductVersion}"
 
-            ' Grunddaten aus Tabellen laden
-            ' Davon abhängige Daten werden in den `focusedRowChanged`-Events der Grids geladen
-            LoadData()
+                lblADRootNode.Text = String.Format(lblADRootNode.Text, Environment.UserDomainName)
+                txtADRootNode.Text = ActiveDirectoryRootNode
 
-            'Spalten an Inhalte anpassen
-            gvUsers.BestFitColumns()
-            viewClients_AllClients.BestFitColumns()
-            viewGroups_AllGroups.BestFitColumns()
+                CurrentUser = userRow
+                CurrentUserId = userRow.GUID
 
-            ' Dragdrop Events für Grids anlegen
-            DragDropManager = New ClassDragDrop()
-            DragDropManager.AddGridView(viewGroups_AvailableUsers)
-            DragDropManager.AddGridView(viewGroups_AssignedUsers)
-            DragDropManager.AddGridView(viewModules_AvailableUsers)
-            DragDropManager.AddGridView(viewModules_AssignedUsers)
-            DragDropManager.AddGridView(viewClients_AvailableUsers)
-            DragDropManager.AddGridView(viewClients_AssignedUsers)
-            DragDropManager.AddGridView(viewClientsGroups_AssignedGroups)
-            DragDropManager.AddGridView(viewClientsGroups_AvailableGroups)
-            DragDropManager.AddGridView(viewModulesGroups_AssignedGroups)
-            DragDropManager.AddGridView(viewModulesGroups_AvailableGroups)
-        Else
-            MsgBox($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt. {vbCrLf & vbCrLf}Bitte kontaktieren Sie den Administrator, wenn dies ein Fehler ist.", MsgBoxStyle.Critical, "UserManager")
-            logger.Warn($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt.")
-            Application.Exit()
-        End If
+                ' Grunddaten aus Tabellen laden
+                ' Davon abhängige Daten werden in den `focusedRowChanged`-Events der Grids geladen
+                LoadData()
 
-        If TBDD_USERTableAdapter.IsUserManagerAdmin(Environment.UserName) <> 1 Then
-            MsgBox($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt. {vbCrLf & vbCrLf}Bitte kontaktieren Sie den Administrator, wenn dies ein Fehler ist.", MsgBoxStyle.Critical, "UserManager")
-            logger.Warn($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt.")
-            Application.Exit()
-        End If
+                'Spalten an Inhalte anpassen
+                gvUsers.BestFitColumns()
+                viewClients_AllClients.BestFitColumns()
+                viewGroups_AllGroups.BestFitColumns()
+
+                ' Dragdrop Events für Grids anlegen
+                DragDropManager = New ClassDragDrop()
+                DragDropManager.AddGridView(viewGroups_AvailableUsers)
+                DragDropManager.AddGridView(viewGroups_AssignedUsers)
+                DragDropManager.AddGridView(viewModules_AvailableUsers)
+                DragDropManager.AddGridView(viewModules_AssignedUsers)
+                DragDropManager.AddGridView(viewClients_AvailableUsers)
+                DragDropManager.AddGridView(viewClients_AssignedUsers)
+                DragDropManager.AddGridView(viewClientsGroups_AssignedGroups)
+                DragDropManager.AddGridView(viewClientsGroups_AvailableGroups)
+                DragDropManager.AddGridView(viewModulesGroups_AssignedGroups)
+                DragDropManager.AddGridView(viewModulesGroups_AvailableGroups)
+            Else
+                MsgBox($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt. {vbCrLf & vbCrLf}Bitte kontaktieren Sie den Administrator, wenn dies ein Fehler ist.", MsgBoxStyle.Critical, "UserManager")
+                logger.Warn($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt.")
+                Application.ExitThread()
+            End If
+
+            If TBDD_USERTableAdapter.IsUserManagerAdmin(Environment.UserName) <> 1 Then
+                MsgBox($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt. {vbCrLf & vbCrLf}Bitte kontaktieren Sie den Administrator, wenn dies ein Fehler ist.", MsgBoxStyle.Critical, "UserManager")
+                logger.Warn($"Der Benutzer '{Environment.UserName}' ist nicht zur Benutzerverwaltung berechtigt.")
+                Application.ExitThread()
+            End If
+        Catch ex As Exception
+            MsgBox("Unexpected Error while loading. Please check the log.", MsgBoxStyle.Critical, "User Manager")
+            logger.Fatal(ex, "Unexpected Error while loading.")
+        End Try
     End Sub
 
     Public Function InitDatabase()