It is two different things you are experiencing.
1. If you stand still the ghosts may not find you - You go (dark) transparent - at that time the ghosts may not get you if they touch you
I don't usually use this because I try not to stop moving and it takes a few seconds to become in this condition
2. And this is the reason you are becoming transparent, for some reason some people have trouble with movement in this game, I think it has to do with computer speed and conection speed. If you get stuck just be glad you didn't crash. Of course there are those that don't know how to play that don't move but for the most part it seems issues are computer related.
I play this game on several computers and have the most issues with it at work where it runs on a network computer and has many filters and firewalls I am sure - in fact if I play games with over four player I am almost sure to experience some stuff more interesting then that. It looks like something out of the movie Matrix with people and ghosts flying all over the place but nothing seems to happen at a normal speed.