use this command for copying files using a wildcard from the GAC to a local folder.
xcopy c:\windows\assembly\Microsoft.SqlServer.Smo*.dll c:\gacdll /s/r/y/c
The above command will continue even it encounters any “Access Denied” errors, thus copying over the required files.
To copy files using the Windows explorer just disable the GAC Cache Viewer by adding a entry to the registry:
Browse to “HKEY_LOCALMACHINE\Software\Microsoft\Fusion”
Add a Dword called DisableCacheViewer. Set the value of it to 1.