I have been testing Ubuntu Feisty on the Windows version of VirtualBox, primarily using the default VM settings. Herd 2 booted correctly initially, but a kernel update a few days ago resulted in boot failure. The previous kernel still booted successfully. Booting from the Herd 3 live cd in the VM results in the same error. The most salient component of the error output is "Bad EIP value". The last screen worth of the error output is in the appended screenshot. I can attempt to get more of the error output if necessary, but I am not certain where or if it would be logged.
I submitted this error to the Ubuntu tracker and someone there indicated it was likely caused by VirtualBox's BIOS: https://launchpad.net/ubuntu/+bug/83820
