Have you run into something like this and are tearing out your hair trying to get past it?
Bringing machine 'vbox' up with 'virtualbox' provider...
==> vbox: Checking if box 'puphpet/ubuntu1404-x64' is up to date...
==> vbox: Clearing any previously set network interfaces...
There was an error while executing `VBoxManage`, a CLI used by Vagrant
for controlling VirtualBox. The command and stderr is shown below.
Command: ["hostonlyif", "create"]
Progress state: E_FAIL
VBoxManage.exe: error: Failed to create the host-only adapter
VBoxManage.exe: error: Code E_FAIL (0x80004005) - Unspecified error (extended info not available)
VBoxManage.exe: error: Context: "int __cdecl handleCreate(struct HandlerArg *,int,int *)" at line 66 of file VBoxManageHostonly.cpp
After more time than I would like to admin, I found the fix. The first step is to download the file found here, created by Jiri Hruska (known to the Internet as Yirkha).
You have to run it as an Administrator, and it will pop up this box:
Then you need to find VirtualBox in Windows Explorer and set VBoxManage.exe and VBoxHeadless.exe to run in Windows 7 Compatibility Mode. To do this, you right click on the file, go to Properties, then Compatibility, and use the box for setting it.
On my system, those files are located in C:\Program Files\Oracle\VirtualBox
Now when you run vagrant up, it should get past the network adapter error because that little tool increases the timeout values for you.
If you want to see the full context of how this fix came to be and read more, take a look at VirtualBox Ticket #14040.