I have a Windows 7 Pro host, and Ubuntu 12.04 LTS guest. I cannot get the shared clipboard working. I have installed Guest Additions 4.1.20 on VirtualBox 4.1.20, have restarted, followed instructions found at http://www.virtualbox.org/manual/ch04.html#idp18411760, and have enabled bidirectional clipboard sharing within VirtualBox options. However, I still cannot copy and paste between the host and guest. Copy/paste works great within the host, and within the guest, but not between the two. I'm out of ideas.