NOTE: The ControlSet number. In my case I had 2 keys, ControlSet001 and ControlSet002. In each of these, I had a mapping to a previous installation of PHP and not the current installation.
Delete these, or change them to point to the directory of your current PHP installation, in my case;
I have no idea why there are more than one controlset, maybe it has something to do with the number of users set up on my machine. What I do know is that IIS looks at ALL of these control sets and sets its mappings according to what it finds there. I also know that after removing these spurious mappings, my system is now ready for a clean install of PHP 4.05.
If anyone knows what these extra registry settings are there for, please let us know.