Hi, i use vb on windows 7 32 host and windows xp guest.
I upgraded to last version 4.1.6 with new extension pack and guest addition.
I have a empty usb filter to let the guest intercept usb drives.
Now when I insert a usb pen drive or disk, the mouse (usb) is locked and I can just use the keyboard to shutdown.
It doesn't happens always, but very often, almost always if the drive is "new" (the host have to load drivers first time).