I've had this problem for a while and haven't been able to come up with a fix. It worked OK at one time and I'm not sure when or what caused the problem. I uninstalled the Updater program with Revo Uninstaller Pro, restarted and then did a new install, but the same problem.

If I select "Download only" for the update and then go to the folder where the update is and click on the update it will install.

I'm on Win 8.1 Pro 64 bit.

I have dual boot (separate drives) with Win 7 64 bit on this PC and the Win 7 install works OK.