help with opening file

Hi I hope someone can help I got my son a new computer for Christmas which has windows 8.1 seem to be having a lot of trouble opening files that I have downloaded
, these sites are on his laptop which was windows 7 and I didn't have any problems with, I am downloading esf 123 version which runs with Half-Life (on steam) and when I try to open it is says cannot verify publisher and it then asks me where I want to open it , i.e. internet explorer, note book etc it won't let me open it at all keeps saying cannot verify publisher, my son uses this site on his laptop with no problem how do I open this file, please help its driving me mad, ps be gentle i have no experience with computers but can follow plain instructions. Thank you

Is this what you are trying to open---

Hi

Yes that is it, it won't let me get to that stage, when I go to open it keeps showing Cannot verify publisher

cluckers72 said:

Hi

Yes that is it, it won't let me get to that stage, when I go to open it keeps showing Cannot verify publisher

Click to expand...

I don't know.
Maybe someone here knows.

The only thing I can think of is maybe you need to change UAC settings.

A picture---



I use that setting because the others annoy me.
& I have a good Antivirus program & Firewall.

Will try this, thanks

cluckers72 said:

Will try this, thanks

Click to expand...

ok.

This is an old program and may not work on Win 8.1 and have been unable to find the system requirements. Perhaps compatibility mode will work.

How do you do compatibility mode

See this tutorial
http://www.eightforums.com/tutorials/6832-compatibility-mode-use-windows-8-a.html

Thanks for this will give it a go