Windows 7 VirtualBox image won't boot and I can't boot in safe mode

I am trying to load a Virtualbox VM using a VHD file that was provided to me. The VHD contains an image for our dev environment on a Windows 7 OS. The wrinkle is that when I try to start up the VM, it gets stuck in a boot loop, never making it past the "Windows is loading files..." screen before automatically restarting.

My googling seems to indicate that the problem is the change in host CPU between me and whoever originally minted the image. The solution requires me to reboot the VM in safe mode and handle it from there, however I can't seem to figure out how. I have beat all the function keys like a madman hoping one would get me there, but that doesn't seem to do the trick. And, since I can't load at all, I can't mess with msconfig.

Any thoughts about how I could deal with the original VM boot problem or how to get into safe mode would be greatly appreciated.

You should ask for an appliance file that contains the virtual machine image rather than just de hdd image, it can be obtained from "exporting" the virtual machine, theres an option in the menu of the virtualbox GUI to do that, an then import it in your computer's virtualbox.

If you want still to recreate the configuration to be like the one in the original VM, yu can ask how it was configurated and check that is the same config (but there are a lot of options).

Maybe an option like acpi config was diferent, and that diference if exist, can be the cause of your problem, but is preferred that you import the appliance (.ova file) instead of try every posible set of options.

Good luck!

For posterity, the problem turned out to be having Hyper-V installed as well. It wasn't running, just installed. It was indicated in the documentation that one must never try to run them both at the same time, but having them both installed is fine. After uninstalling Hyper-V, a shiny new VirtualBox VM with the VHD as the hard drive booted up with no problems, so it looks like these two programs cannot coexist, at least on my machine.