aster

It seems the Program Guard element of "Online Armor" was blocking the execution of "SetupFrontEnd.exe". For some reason it didn't ask me for permission to run it, but after a reinstallation of Online Armor and several reboots, I've now installed the update. So this problem would seem to be symptomatic of a third party app. blocking elements of the installation. Whether that's true in the OP's case is another question.

Having exactly the same problem with Vista 32. Previously had 3.36 installed - that wouldn't run (for some reason) and wouldn't uninstall either - Windows indicated a problem with the installer, so I tried to remove it with WICU, but to no avail. Installation of 3.5.1 gets as far as extracting files then...nothing.