Just got a 13" M'book Air, great. 1. Why doesn't my trackpad 'tap' facility work in 'guest' mode? (I have to manually click) 2. Again in guest mode, when I surf on safari and 'scroll' there is a strange horizontal rippling prism like effect running across the screen about half way down. It's only a few millimetres wide. 3. Is there any way I could activate a few apps for someone using the gust account? It seems the standard setup provides nothing but safari surfing.