Here’s a quick tip on a not so obvious bug you can have with VirtualBox. I took ownership of a Windows 7 virtual machine from a colleague. I copied the vdi file from his machine to mine, added the appliance to VirtualBox and tried to boot the VM so I could do the base configuration to change licences and domain information… Only to find the machine was stuck in a boot loop. The virtual BIOS would flash up, say ‘Windows is loading files’, then the machine would reboot and the cycle would continue.

It took several hours and several copies to spot the cause of this issue, including checking my machine to make sure virtualization was properly configured. I did have a VT-x related error to start with that required me to fully enable Hyper-V support and *then* disable it, but ultimately once that was solved – my reboot loop issue was caused by the system architecture. Although the host and VM were both 64bit, and the VM was set as 64bit on my colleagues machine – when adding the VM to VirtualBox, the VM was automatically being set to being a 32bit OS. Once changingthe settings in VirtualBox, the VM booted instantly.

Bloody annoying – after I’d wasted several hours trying to figured out what on Earth was going on.

If you’re ever stuck in a boot loop on VirtualBox after migrating VM’s, check the architecture to be sure it hasn’t changed during migration!