Virtual Box upgrade is stalled due to this request from Virtualbox: "Files in use Some files that need to be updated are currently in use. The following applications are using files that need to be updated by this setup. Close these applications and then click Retry to continue the installation or Exit to exit it. virtualbox Manager Process id: 168 " I've shut down the Virtualbox program during upgrade yet I still get the above issue, any ideas as to solution? Thanks in advance.