Mohaa Expansion Pack Grief

Hi all.
Going through my old games I decided to have a blast at MOHAA.
It wouldn't install until I ran the .exe as an administrator then it installed fine but wouldn't load.
Looked online and it is a common issue.
Used a No CD crack and all was well.
Same with Spearhead expansion pack.
Tried to install Breakthrough but that won't even get to putting the product key in.
I get two boxes.
The first says there is a virus, obviously not, it's an original game.
The second tells me the wrong key has been put in but I didn't even get to that stage.
I've tried disabling anti virus and firewalls to no avail.
Any clues?

 

I thought I'd try reinstalling MOHAA so the original .exe is there.
Same grief.

 

Well push me in a pond and call me Brenda!
I decided to try it in my second DVD drive and bingo, first time.
Loads of folk have had grief lately, what's going on?
Why are .exe files on game DVD's being flagged as a risk?