How to fix the "No installed Python found" bug with Blender 2.49a with Python 2.6.2 Installed

At times, if you want to launch Blender 2.49a, a message may appear on the Blender startup command prompt. This message is:

Compiled with Python version 2.5.
'import site' failed; use -v for traceback
Checking for installed Python... No installed Python found.
Only built-in modules are available. Some scripts may not run.
Continuing happily.

If you have two or more Python installations and uninstalled one of them (not Python 2.6.2, as needed by Blender 2.49a to run properly), that message may appear. To fix the problem, reinstall Python 2.6.2 here (depending on your OS): http://www.python.org/download/releases/2.6.2/
Please do not open the installation file (depending on your OS, again) fron the Web, as opening the file may cause problems with the installation progress. There's no need to restart your computer, after you reinstalled Python 2.6.2 successfully, run Blender and the above message is not displayed unless you have installed another Python version.