To avoid possible security and privacy issues, a suspended Windows virtual machine can be completely locked from user interaction and viewing. When this option is enabled and a virtual machine is suspended, the Windows desktop in the virtual machine window (and in the Parallels Desktop Control Center) is replaced with a black background and the Windows session is interrupted. When the virtual machine is resumed, the Windows session is remained locked and the user will have to enter their credentials or authenticate (depending on how Windows is set up) to unlock it and see the Windows desktop.
To enable or disable this option:
Open Parallels Desktop and select the desired virtual machine (e.g. the source virtual machine when preparing it for mass deployment).
On the Parallels Desktop menu bar, select Actions > Configure to open the virtual machine configuration dialog.
Click the Security tab.
Depending on your needs select or clear the Always lock Windows on suspend option.
Close the dialog.
Note: The Always lock Windows on suspend option is available only for virtual machine running Windows with Parallels Tools installed. For all other virtual machines, the option will be hidden.