After installing the incorrect version of Tuxedo for Windows, you may encounter an error trying to install the correct version, complaining that the tuxdirkey is already set.

Run the registry editor (regedit) and delete the keyset:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\ORACLE\TUXEDO\

Warning: Changing anything in the registry could cause major system issues, be very careful.