I just installed the new security update on my mbc and now the damn thing wont start up! when i power on, the machine is running, i can feel the hdd spinning etc, and the screen turns on, just it is black or a very dark grey. No apple logo, no "ta-da!" sound....whats going on?! Do i use the Tiger DVD? edit: YAY! after resetting everything else, resetting the PRAM did it!!