When I tried installing XenServer 6.5 from USB stick I was greeted by a nice blue screen with a kernel panic upon first boot. I tried using another USB stick to make sure it wasn’t an issue with the pen drivebut I got the same error message.
The solution was to use Universal USB Installer to create the bootable USB drive (I was previously using UNetbootin). For some reason, this allowed XenServer to boot successfully without any issues.
Thanks to Dave Thijssen whose blog post made me give Universal USB Installer a try ;)