I'm using Kubuntu 12.10. I have the latest version of VirtualBox(4.2.4) with expansions installed and guest addition also. I'm trying to install Windows 7 but it freezes at the second step: expanding files (random percent). I even tried to install Vista but is happening the same thing. Is there a bug? Do you happen to know a workaround? Or at least there is another free virtual machine I can use to install win 7?