Windows Longhorn is unstable, unfinished alpha/beta software from ~2003–2006. It is for historical/educational use only . Do not use it as a daily OS. It will crash, corrupt data, and has known security vulnerabilities.
Once Longhorn boots to desktop:
: Most Longhorn builds have an expiration date. To make them boot, you must trick the VM's clock. windows longhorn qcow2 work