Virtualbox VM not booting from old separate hard drive

[user323456]

I have a bit of a problem with Oracle's Virtualbox. Before I upgraded my pc with an SSD I ran VB with 64-bit Ubuntu on my Win7 system, all worked good etc. Now I'm running my pc off the SSD which I installed, complete with a fresh Win7. I still want to be able to access my old Ubuntu VM though, so I found the folder containing the .vbox file and the much larger .vdi file (Users\USERNAME\VirtualBox VMs\Ubuntu64), downloaded the latest VM VirtualBox software and ran it on my new SSD Win7 install, using "Machine"->"Add" in the VM manager to reference my old .vdi/.vbox file.

First problem was that it complained about my CPU not having hardware virtualization enabled, so I checked the BIOS; it was enabled (this being a i7-2600k), and after checking that problem went away. Now, however, when I run it, I get a GNU GRUB screen with 5 options: Ubuntu, Ubuntu recovery mode (both with linux 3.2.0-24-generic), previous linux versions, and two memory tests (memtest86+ and memtest86+, serial console 115200).

I've tried the top two options with nothing but a black screen following. I really want to be able to get back into this VM, since I had some good code there...

Also not sure if this is relevant but when I start the VM manager it gives me a warning saying some virtual hard disks may not be accessible. When I hit 'check', my Ubuntu64.vdi appears under 'hard drives', with type normal, storage details: dynamically allocated, and attached to: Ubuntu64.

[noteirak]

Please post the VM log file as described in Minimum information needed for assistance.