Norton Internet Security - Preinstalled trial version wouldn't allow me to install other apps

Hi Guys,

I have just recently purchased a Toshiba Laptop that came preinstalled with Windows 8.1 and a trial version of Norton Internet Security.

I would like to replace the trial version of Norton Internet Security with Norton 360 (which I already have a licence).

I also want to install other apps e.g. Office 365, Google Earth, etc.

But whenever I tried to install a new apps, I would be able to download the apps setup programs but when I tried to Run the Setup, a message would come up showing that it was being scanned. But then nothing happens after that!

I suspect it could be Norton Internet Security stopping me from executing the setups.

Any ideas how I can get past this barrier?