Index: source/windows/Main.pas
===================================================================
--- source/windows/Main.pas	(revision 177)
+++ source/windows/Main.pas	(working copy)
@@ -34,7 +34,7 @@
     property ConfigFileDestination: WideString read FConfigFileDestination write FConfigFileDestination;
     property InnoDBLogFileSize: WideString read FInnoDBLogFileSize write FInnoDBLogFileSize;
     property InnoDBDataHomeDir: WideString read FInnoDBDataHomeDir write FInnoDBDataHomeDir;
-    property DataPath: WideString read FDataPath;
+    property DataPath: WideString read FDataPath write FDataPath;
     property CnfDataPath: WideString read FCnfDataPath write FCnfDataPath;
     property InstallationPath: WideString read FInstallationPath;
     property Port: Integer read FPort write FPort;
@@ -386,9 +386,9 @@
   FVersion := Version;
   FInstallationPath := IncludeTrailingPathDelimiter(InstallationPath);
   if (DataPath <> '') and (DataPath <> '\') then
-    FDataPath := IncludeTrailingPathDelimiter(DataPath)
+    FDataPath := IncludeTrailingPathDelimiter(DataPath) + IncludeTrailingPathDelimiter('Data')
   else //Backward compatibility
-    FDataPath := IncludeTrailingPathDelimiter(InstallationPath);
+    FDataPath := IncludeTrailingPathDelimiter(InstallationPath) + IncludeTrailingPathDelimiter('Data');
   FServiceName := ServiceName;
   FConfigFileDestination := CnfFileDestination;
   FExistingDataDir := ExistingDataDir;
@@ -827,19 +827,23 @@
         NewPasswordPnl.Top := 80;
 
       // Check to make sure the datadir for this instance matches it's config file
-      T := Tnt_WideStringReplace(CurrentInstance.DataPath + 'Data' + PathDelim, '\', '/', [rfReplaceAll]);
+      T := Tnt_WideStringReplace(CurrentInstance.DataPath, '\', '/', [rfReplaceAll]);
       if ((not WideSameText(CurrentInstance.CnfDataPath, T)) and DirectoryExists(CurrentInstance.CnfDataPath)) then
       begin
-        MessageDlg('The defaults-file used by the service named ' +
-        CurrentInstance.ServiceName + ' contains the following option:' + #13#10 +
-        '    datadir="'+ CurrentInstance.CnfDataPath + '"' + #13#10#13#10 +
-        'However, if this service is reconfigured with the Config Wizard at' +
-        ' this time the new defaults-file will contain the following option:' +
-        #13#10 + '    datadir="' + T + '"' + #13#10#13#10 + 'When started, ' +
-        'this service will use the datadir specified by the new option. If this ' +
-        'is a mistake, close the Wizard and either manually move your data ' +
-        'directory to the new location or Modify the installation to point to ' +
-        'the correct data path.', mtWarning, [mbOk], 0);
+        if InstanceFromCommandLineParams = True then // CommandLine param wins.
+          MessageDlg('The defaults-file used by the service named ' +
+          CurrentInstance.ServiceName + ' contains the following option:' +
+          #13#10 + '    datadir="'+ CurrentInstance.CnfDataPath + '"' +
+          #13#10#13#10 + 'However, if this service is reconfigured with the ' +
+          'Config Wizard at this time the new defaults-file will contain the ' +
+          'following option:' + #13#10 + '    datadir="' + T + '"' +
+          #13#10#13#10 + 'When started, this service will use the datadir ' +
+          'specified by the new option. If this is a mistake, close the Wizard ' +
+          'and either manually move your data directory to the new location or ' +
+          'Modify the installation to point to the correct data path.',
+          mtWarning, [mbOk], 0)
+        else                                  // CNF param wins.
+          CurrentInstance.DataPath := CurrentInstance.CnfDataPath;
       end;
     end;
   end;
@@ -1736,7 +1740,7 @@
       Vars.variables_num := Vars.variables_num + 1;
 
       Vars.names.Add('datadir');
-      Vars.values.Add('"' + Tnt_WideStringReplace(CurrentInstance.DataPath + 'Data' + PathDelim, '\', '/', [rfReplaceAll]) + '"');
+      Vars.values.Add('"' + Tnt_WideStringReplace(CurrentInstance.DataPath, '\', '/', [rfReplaceAll]) + '"');
       Vars.variables_num := Vars.variables_num + 1;
     end
     else