VirtualBox - How to solve VERR_CPUM_INCOMPATIBLE_XSAVE_COMP_MASK error

1. Right click the VM in the manager and click "Discard Saved State ...".

2. Run the VM.

VMWare - How to solve "This virtual machine appears to be in use" error

If you are certain that the guest is truly not running, go to the guest's folder and delete any .lck files and folders.

You can identify the configuration file by looking at the Summary view of the virtual machine.