When installing Vault Server, one of our partners reported this issue.
Error 1920. Service 'MSSQL$AUTODESKVAULT' (MSSQL$AUTODESKVAULT) failed to start. Verify that you have sufficient privileges to start system services.
Now, time was short for this issue as this occured at a conference, so we did not have time to fully investigate. Nor did we search the web for more information. We made sure that the User Account Control was disabled as per the ACG.We checked that the Anti Virus was disabled and that the logged in user was an administrator.
We overcame this by manually installing SQL 2008 Express R2 as per the Advanced Configuration Guide. Then installed Vault Server. Because SQL was already installed, up and running, the Vault Server install was then successful.