Installation problem

Hi all,
I have a strange problem. I own quite a few games, and being disabled play them quite often. The other day I decided to clean install windows to get rid of a lot of rubbish on my pc.
Now a few of my games will not install. I get the message along the lines of ' Make sure you are running the correct version of the game 64bit, etc,etc...
I am running win7 ultra 64bit so why is it I could run the games before but not now??

This has me pulling what hair I have left out!

Thanks

Are you using Elevated Admin Rights when you try to install? what I mean is are you Right Clicking on the EXE file and use "Run as Administrator"? is you login the main Admin?

I can't think of anything else at the moment.

Thanks, that seems to have solved it.