Check and select Windows 7 from the dropdown.
If you are using a physical disc or a mounted ISO, Windows might fail to find the "drive" because the assigned letter has changed or isn't recognized by the game’s pathing. Right-click the button and select Disk Management . Find your CD/DVD drive (or virtual drive) in the list. blur no cd dvd-rom drive found
Use software like PowerISO to mount a disc image of the game. Check and select Windows 7 from the dropdown