On my HP/Compaq Presario laptop, I press fn + F5 to refresh. If I use shift and F5, a dialog asks me to confirm if I want to reload the page, or not.
Pressing the function keys alone offer special functions like brightness (F2 and F3) volume (F9, F10, and F11) and other controls, which I am not always sure what they do. Must read that manual one day...