The 2.6.4 docs (at http://docs.python.org/using/windows.html) do not give enough detail for an ordinary user to work out how the registry key HKLM\SOFTWARE\Python\PythonCore\version\PythonPath actually works. It says: Modifying the module search path can also be done through the Windows registry: Edit HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\version\PythonPath. It should say: Modifying the module search path can also be done through the Windows registry. To add a folder to the module search path, create a subkey under HKLM\SOFTWARE\Python\PythonCore\version\PythonPath. The subkey name is not important (but might, say, identify the package being added to the search path). Put the name of the folder you want searched in the default string value of the key you have created. Specify multiple folders as a semicolon-delimited list. If you create more than one subkey, all will be used, in alphabetical order of subkey name. If a folder appears in more than one subkey then it will appear only once in sys.path, in the position corresponding to the first mention. Do not amend the list of folders given in the default value at the PythonPath key level. Installers create this value but it is a holdover from earlier versions of Python and amending it has no effect.
If, as the OP indicates, the value of the key itself is ignored, this should be mentioned in the doc, especially if it normally has an apparently valid value.
