I tried everything to no avail.
I cleaned some problems with CCleaner.
I killed the folder and the registry entries with the UID you provided me.
Then since the UCAWA lobby didn't istalled still, I used the fake .exe trick and tried to install the old version.....guess what, I have the same exact error message saying that another version of that software is already installed on the system and for that the installation cannot proceed.
I think I can live without the lobby until my next format.
Thanks for your help SC, I don't wanna waste it anymore.
If you wanna me to try something other just let me know and I'll be happy to do so.