Hello! Thanks for the clarification - I was starting to suspect it was a Windows 7 issue. My main rig is Windows 10 so I'll just install DO on that at some point. Here's the conundrum however, that system does not have a DVD drive. Would it work if I copied the contents of my disc to a USB flash drive and installed the game that way? I'd need a no-CD crack however...
Failing that option, an investment in an external DVD drive would do the trick.