Hi @proteus yes this is very odd and not something we have heard any reports of. Were you hosting any particular 3rd party plugins inside of Scaler 3 which may be causing an issue? You might like to consider a clean install of Scaler 3 in case there is an installation issue. Instructions for this are on the Known Issues forum page.
To recover your Cubase project, perhaps you could uninstall Scaler 3, then open your project, The project should open and simply state that the Scaler 3 plugin is missing. Then you can backup the project without Scaler 3 under a different file name.