incapaz de fazer parada vagante

Question

Quando tento executar vagrant halt , obtenho o seguinte:

An action 'halt' was attempted on the machine 'default', but another process is already executing an action on the machine. Vagrant locks each machine for access by only one process at a time. Please wait until the other Vagrant process finishes modifying this machine, then try again.

If you believe this message is in error, please check the process listing for any "ruby" or "vagrant" processes and kill them. Then try again.

Como posso descobrir o que está usando a máquina 'padrão'?

Obrigado!