Se você pesquisar na Internet omnisapient, você vai cair no fórum do VirtualBox delineando um problema como o seu , que tem a próxima solução:
My Solution:
I went into the folder "C:\Users\COMPUTER_NAME\.VirtualBox\Machines\VM_NAME\" and saw two xml files but for some reason they both had suffixes.
1. VM_NAME.xml-prev
2. VM_NAME.xml-tmp
So it simply just couldn't find "VM_NAME.xml" because it technically didn't exist.
I made a copy of the "VM_NAME.xml-prev" file and renamed the copy to "VM_NAME.xml"
Restarted VirtualBox and it worked just fine