Ubuntu – Implementation of the USB 2.0 controller not found! after upgrading to virtual box 4.0.6

I got a strange error message when I tried starting Ubuntu after upgrading to latest virtual box 4.0.6..

At last I was able to fix it by editing the settings XML file manually

Go to c:/users//.virtualbox/Machines//.xml

change the line having enabledEhci=true to enabledEhci=false

did the trick !