>I'm trying to rename a folder with xxx.x syntax to xxx.y and the rename comamand does not works! Can anybody tell me how to rename a directory/folder name ?

You need to use either the Win32 API call MoveFile() or use the Windows Script Host. Using the WSH is far easier.

oFSO = CREATEOBJECT("Scripting.FileSystemObject")
oFolder = oFSO.GetFolder("C:\MyOldFolder")
oFolder.Name = "MyNewFolder"