Remember your DOS, my son. Keep in mind that when you use dosbox, your c:\ directory is the directory you mounted the drive on. So if you mounted your c drive as c:\sierra\kq5, the drive thinks that the directory is c:\ when it’s really the folder that your game is in. Just to be on the safe side I like to mount c:\sierra as my c: drive and then type in cd kq5 to get to c:\kq5. Then when I go to save my game the save directory appears as c:\kq5. You don’t have to do it, but it’s a good way to make certain your save game stays in the same folder as your game’s content.
Also, make sure you’re not mounting your d drive as your c drive. Mount your d drive using “mount d d:\” then mount c as the directory your game is installed in. Then go to c: and run using the game’s c drive location.