1. Create Windows installer with Python 2.5 from attached project.
2. Install it with Python 2.6.1.
3. The post-installer will fail with error message: 
*** run_installscript: internal error 0xFFFFFFFF ***

The code causing this is:

import socket

and the actual error is:

ImportError
DLL load failed: The specified module could not be found.
  File "<string>", line 6, in windows_binary_install
  File "c:\apps\python26\lib\socket.py", line 46, in <module>
    import _socket

If the installer is created with Python 2.6.1, it works fine. 

The problem was noticed in the Robot Framework project and the issue can
be found from http://code.google.com/p/robotframework/issues/detail?id=196.

This problem was first asked as part of issue
http://bugs.python.org/issue4566, but Martin v. Löwis recommended to
open new issue for this.

Was the 2.6 installation "for all users", or "just for me"? What Windows
version are you using?

Python 2.6.1 was installed with option all users. I have admin rights
and the Windows version is:
XP Professional
Version 2002
Service Pack 3

Not sure if there is much to be done here; I don’t know if it is a reasonable expectation that an installer created with 2.X still work with 2.X+1, and anyway only 2.7 could get a bugfix now.

Installers "ought to" work for subsequent versions if they contain pure-Python packages (i.e. no extension modules). I agree that the issue is obsolete for 2.x, but it may still exist for 3.x.

Thanks, keeping it open.  If I manage to get a VM set up I will see if this is reproducible.