Many times, admins have complained that they could not access or could not boot a virtual CDROM that was inserted or an ISO file that was mapped.
And so many times, the cause of this issue is just a simply click. To access a virtual CDROM, that CDROM must be connected. If you look at the graphic below, you can see how the device is both connected and connected at power on. Connected devices are connected after the VM boots where as connected at power on devices, are connected before the VM boots. To boot a new OS CD, that CDROM needs to be connected at power on.
Figure 1