The reason for this error is explained in this discussion thread. To recover from this error, follow these steps below:
- Click on the OK button and come to the VirtualBox manager.
- Click on the VM that threw this error and click on the System.
- Click on the Processor tab and reduce the number of CPUs to 1.
- Click on OK and save your changes.
- Now start your VM by selecting it and clicking on Start button or just by double clicking on the VM.