母雞CentOS 7 64位元DVD版本，rpm安裝了virtualbox虛擬機器。
新建了兩台虛擬機，一個名為windows7，一個名為centos7minimal。
圖形介面下開關機機一切正常，但在無介面或沒開啟virtualbox視窗時，啟動windows7失敗，啟動centos7minimal成功。

[shellus@centos7 ~]$ VBoxManage startvm windows7 --type headless
Waiting for VM "windows7" to power on...
VM "windows7" has been successfully started.
[shellus@centos7 ~]$ VBoxManage startvm centos7minimal --type headless
Waiting for VM "centos7minimal" to power on...
VM "centos7minimal" has been successfully started.
[shellus@centos7 ~]$ VBoxManage list runningvms
"centos7minimal" {20093899-79cd-4d49-86fd-594ada458e70}

難道windows7虛擬機器沒有圖形介面就無法運作嗎？只有server版本的windows才能無介面運作？