It only takes a slight detour via the registry to solve this
* Open the Registry Editor by clicking on "Start/Run", type "regedit" and click on "OK".
* Navigate to the "HKEY_Classes_Root\Directory\shell"key.
* Select the incorrect command and delete it. Now you just have to restore the desired standard action.
* Navigate to the key "HKEY_Classes_Root\Directory\shell".
* On the right hand side of the Registry Editor window, double click the Value Name "Default".
* Replace the name of the undesired context command with "Open". This way, you transfer further control to the file type "folder".
* Now, open Windows Explorer. Click on "Tools/folder options".
* Select the entry "None Folder" in the "File types" tab. (in Windows 2000, select "Folder"). Click on "Advanced".
* Only one action other than "Open" can be defined in the dialog box, which should be set "As default".
* Confirm the dialog box with "OK" and "Close".
Note : Microsoft has equipped Windows Xp with both file types "File folder" and "Folder" and this in itself is quite confusing for some. What further complicates the matter is that both are responsible for settings in the context menu of folders and have the same effects. For example, if you have defined a new standard action for "File folder". Windows ignores the standard action for the file type "Open" command cannot be defined as default again via the Folder options dialog box. The correction can only be made via the registry.