VirtualBox - USB devices greyed out in Guest OS

Ubuntu 10.04 Host
VirtualBox 4.0.x
Windows 7 Guest

I had this problem previously (on a different OS install) running VirtualBox 3.x with a Windows XP Guest, and steps 1-2 below solved my problem.

This time, running VirtualBox 4.x with a Windows 7 Guest OS, I needed a 3rd step. Guest OS may not have mattered. Shortly after installing the new VirtualBox, I installed the VirtualBox Extension Pack to support USB 2.0 devices.

Following steps 1-2 removed the "greyed out" problem, but the USB devices would not mount and were inaccessible in the Guest OS. I had to open the Guest OS properties and enable the USB 2.0 (EHCI) Controller option.


Steps:

1. Add your Ubuntu account to group "vboxusers". Go to System > Administration > Users and Groups - then click "Manage Groups", then double-click "vboxusers" then check/enable your account in there.
   
2. Reboot (or maybe log out/in? - untested)
   
3. Enable USB 2.0 in VirtualBox. Open VirtualBox (not Guest OS), click Settings button for Guest OS. Click USB. Check the Enable USB 2.0 (EHCI) Controller box.