Feil i opprett_stoykilder
Check the AutoCAD command line after pressing "OK" in the error dialog.
If it says: "Feil i sa_insert", check if Novapoint Noise's internal layer is locked. You find the name of the layer in Global Settings (default is "_Novapoint_Støy_interne_data_IKKE_TIN_DETTE_LAGET"). If it is locked, unlock it and things should work again.