I recently setup the latest and greatest (13.04) on my laptop. I still have to work on Visual Studio so I installed Virtualbox (4.2.12) to setup a Windows VM.
All goes well until the point where you have to install the guest additions as it is needed for the USB support. Now a dialog box shows up prompting you for your password. Here’s the kicker: no matter what you put in, even if is the CORRECT password, it’ll tell you have entered a wrong password and not let you continue.
I did a lit bit of searching on the internet and found the answer here.
Pull up a terminal and type this:
sudo VBoxManage extpack install <tarball>
where you would substitute
sudo VBoxManage extpack install Oracle_VM_VirtualBox_Extension_Pack-4.2.12-84980.vbox-extpack