When I start my Ubuntu Guest OS in the VM, a stream of errors fly by and here's what I see at the end.
mount: mounting /dev on /root/dev failed: No such file or directory
mount: mounting /sys on /root/sys failed: No such file or directory
mount: mounting /proc on /root/proc failed: No such file or directory
Target filesystem doesn't have /sbin/init.
No init found. Try passing init= bootarg.
BusyBox v1.13.3 (Ubuntu 1:1.13.3-1ubuntu11) built-in shell (ash)
Enter 'help' for a list of built-in commands.
(initramfs)
My host system is Windows XP, my guest system is Ubuntu 10.04 with Guest Additions and my VirtualBox version is 4.0.12.
I created a second VM and remounted the existing hard disk "Ubuntu 10.vdi" as the boot drive and got the exact same error. From searching around the internet, it seems I might be able to repair the drive, but I don't know how to do it from Windows XP or another Ubuntu VM.