i think if your graphic card support turning off hardware acceleration,it's not greyed out.if not it's always greyed out.i have Intel HD Graphics,i have same greyed out.before when i have no graphic card,vga graphics driver.it's not greyed out.so it's graphic card support it or not.so don't bother,it's ok.if u really want it,then contact u'r graphic card manufacturer e.g.intel,ati,amd,nvidia whatever.i'm not an expert,hope i help.