Ubuntu 中VirtualBox OSE出现Unknown error creating VM (VERR_HOSTIF_INIT_FAILED)

我的网卡共享是Host Interface.可能是几天更改了机器的hostname，所以出现了这个错误。
google了一下，解决方法如下：
详见：http://www.giannistsakiris.com/index.php/2007/11/25/unknown-error-creating-vm-verr_hostif_init_failed/

Unknown error creating VM (VERR_HOSTIF_INIT_FAILED).
VBox status code: -3100 (VERR_HOSTIF_INIT_FAILED).

while trying to start your VirtualBox on Ubuntu, then it's probably because the user by which VirtualBox is running does not have read/write permissions on /dev/net/tun. To solve the problem run this commands:

sudo chgrp vboxusers /dev/net/tun
sudo chmod 660 /dev/net/tun

then add the user that is going to use VirtualBox to the vboxusers group. Run the following command:

sudo gedit /etc/group

Find the vboxusers group:

...
mysql:x:121:
vboxusers:x:1001:
postfix:x:122:
...

And add all the users that will use VirtualBox into it:

...
mysql:x:121:
vboxusers:x:1001:giannis
postfix:x:122:
...

Save the file and exit gedit. You should not get this error any more.