So I'm running Kubuntu 12.10 x64:
uname -v -p #29-Ubuntu SMP Fri Oct 19 10:26:51 UTC 2012 x86_64
and Virtual Box 4.2 installed from the VBox repositories.
Any time I try to install a 64-bit OS as a guest the install fails and crashes w/ a kernel panic on Ubuntu or bombs in Windows 7 before it will boot.
Am I missing something?