ResidualVM is very much real, but still under development. The game is completable with it, but there might still be bugs here and there. Also, they only offer daily builds, i.e. the current development version of the software on a given day, so if you're unlucky you might get it on a day when a recent change in the code broke something. There will be a stable version (i.e. a version having received extensive testing from the community before release) someday, probably reasonably soon, but it seems they're not quite there yet.
So playing GF with a daily build of ResidualVM should probably work fine, if you're willing to put up with a few rough edges here and there. The
Grim Fandango launcher might be a safer option otherwise.
(Oh, and Norton is a joke, not to mention a resource hog. You should get rid of it and switch to something else.)
