Sorry about the confusion, I was a little tired when I posted my question. Whatever the latest patch was, 1.05 or whatever caused Combat Mission to not recognize that I had the CD in the drive and wouldn't allow me to play the game.
I've noticed that when I try to patch Combat Mission from 1.112 to 1.5 it tells when I start the game that I don't have the CD in the drive, but I of course do. When I restore the exe file to the older version the problem goes away. What's going on?