Why does the Deployment Workbench show version 4.1 after installing MDT 2008 Update 1?
The reason why Microsoft Deployment Workbench shows Version 4.1 is due to caching that can occur with certain DLL’s. If you previously had MDT 2008 installed, the version was cached and unfortunately does not update properly after the installation of MDT 2008 Update 1. To update the version number, you can delete the following registry entry and then it will update with the correct version number. HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\@C:\Program Files\Microsoft Deployment Toolkit\Bin\Microsoft.BDD.WorkbenchResources.