Download an install a software like Virtual CloneDrive, MagicDisc or DAEMON Tools Lite, and create a virtual CD drive, the game needs to run in a pc with a CD drive, it doesn´t matter if it´s empty, just to have a cd drive listed on My PC is enough (I have an old DVD-RW that doesn´t even read any cd

but when I removed it GP4 started with the "insert the CD" problem, so I simply reconnected the DVD drive and everything was normal again. I guess the executable checks if there´s an optical drive at the start).
Here you can download some free virtual cd tools:
You must be registered for see links
