今天新建了用户之后，打开VirtualBox，却报出如下错误：
Failed to create the VirtualBox COM object.The application will now terminate.Callee RC: NS_ERROR_FACTORY_NOT_REGISTERED (0x80040154)
这咋回事啊，怎么突然就不能用了呢，无从下手。
查了下，有关于这个问题的都是国外的，而且大多没解决方案，找到一篇靠谱的：
Solve NS_ERROR_FACTORY_NOT_REGISTERED on VirtualBox 4
If you setting up VirtualBox on a server you will probably try to set users and groups by you preferences. Changing UIDs and GUIs by your preference after VirtualBox is installed could bring you in a inconsistent situation and you get this message:
VBoxManage: error: Failed to create the VirtualBox object!
VBoxManage: error: Code NS_ERROR_FACTORY_NOT_REGISTERED (0x80040154) - Class not registered (extended info not available)
VBoxManage: error: Most likely, the VirtualBox COM server is not running or failed to start.
This cryptic message is in fact saying you that something is wrong with users or groups. But what? Not the libraries, not any file created during the VirtualBox installation but… the files created in the /tmp folder. Simply delete all related thing, even the hidden ones, and you will be fine again!
大致意思是说，在/tmp目录下，有临时文件被锁住了，包括隐藏的文件。
切换到我的/tmp目录下，根据文件名大概判断一下发现有个.vbox-liyd-ipc 的文件，删除它：
> rm -rf .vbox-liyd-ipc
重新启动VirtualBox正常！