Nope, sorry – this seems out of scope from this article which is about getting the thing off the ground. Once VirtualBox can start a VM, then my work here is done.

One thing that I can guess is that there may be some weird interaction between the older guest tools installed in the Windows XP VM and the newer VirtualBox – not that I’ve seen anything like this before. You can try loading the Windows VM in “safe mode” and if you can load it like this then its probably a good idea to back up all the VM data and reinstall.