Thanks for responding. Both accounts are set up as “administrator”, as far as I can tell they have the same access rights.
This is unbelievably frustrating – there doesn’t appear to be any logical reason why the project is suddenly accessible from one user account but not another, especially as the issue is on the account where the project was developed and it is the same account where Vegas was originally installed
Anyone know where the ProDad FX presets are stored, so at least I can continue the project in the other account?