Two last things I can think of to try:
First try changing C:\Archivos de programa\freescale\ to C:\Program Files\freescale\, and run the installer. If that works, the problem was that the installer didn't recognize the different name for the Program Files directory. Be sure to change the directory name back.
Second, if that doesn't work, something must be botched in the CodeWarrior install. So, uninstall CodeWarrior using the Windows Add or Remove Programs control panel. Then, reinstall CodeWarrior. If you can, try to use the defaults, especially on the directory paths. Then try running the 6.3.1 installer.
If that doesn't work, you'll have to file a service request.
---Tom