A more recent version....Installation Terminated

I was in the process of installing Symantec Desktop Encryption 10.3.1.13100 on a Window 7 Professionale client when a window popped up saying:

"A more recent versione of Symantec Encryption Desktop is already installed. Installation terminated", with a OK button.

Clicking on the OK button didn't terminate the installation process though, it continued with a lot of errors saying the it couldn't write the registry because the registry folder SOFTWARE\PGP Corporation\Common was missing....

I am positive SDE has never, ever been installed on that host before.

The only Symantec product already existing is Symantec VIP. Any known incompatibility with that product?

Any suggestion?

Thanks for your help

Roberto