I renamed the VBoxDD.dll file to VBoxDD0.dll and then copied the x64 version of VBoxDLL.dll to my Virtualbox directory since I am running windows 7 x64. I then copied the vminstall.exe to my virtualbox windows 7 x86 machien and installed it. I used the defaults and hit ok. When my VM reboots it gets stuck on “Starting Windows”.
Make sure you have vmmon running and do not select ICH9 chipsets at the moment, this is an bug of the actual release. It can only work on PIX chipsets.