I purchased this game from GOG, downloading is no problem. When it comes to installing I get this message "Unable to execute file in temporary directory. Setup aborted. Error 5: Access is denied. I'm administrator of the user account on this pc.. I'm the only account. My OS is Window 7 64-bit. I'm at a lost as to why this is happening.
Any help will be appreciated.

Try suggestions posted or [url=https://answers.microsoft.com/en-us/windows/forum/windows_7-performance/unable-to-execute-files-in-the-temporary-directory/0d441663-6167-420d-b936-53f9c3d17898]here

I have done that. Another strange thing is that I downloaded Dungeon Keeper and Dungeon Keeper 2 and they installed with no error message. I never have been prompted by User Account Control.

Thank you for your reply.

Hmm, so DK and DK2 installed properly but M&M8 didn't. Try copying the installer to another location and run it from there, also with admin rights (right-click => Run as..). Disable anti-virus software and don't install the game into the Program Files folder but into a custom one on C: (e.g. C:\GOG.com\).

Turning off anti-virus software WORKED!!!! Thank you very much.